Input to DYNMOD 1. General Information The input description to the DYNMOD module is divided into 5 sections, each section describing one data-section referred to as A-E. Data Group A: Control Information Data Group B: Free Vibration Analysis Data Group C: Regular Wave, Time Domain Analysis Data Group D: Irregular Wave, Time Domain Analysis Data Group E: Time Domain Procedure and File Storage Parameters Three different types of analysis are possible. Complete input for these types is shown in the list below. Type number 1, Free vibration, requires the data sections A and B. Type number 2, Regular wave, requires the data sections A, C and E. Type number 3, Irregular wave, requires the data sections A, D and E. 2. Data Group A: Control Information This data-group is mandatory for all types of analysis with DYNMOD. The prescribed sequence must be followed. 2.1. Principal run parameters 2.1.1. Data group identifier, one input line DYNMod CONTrol INFOrmation CHVERS CHVERS: character(8): RIFLEX input file version, e.g. 3.2 2.1.2. Heading, three input lines Heading, line no 1 Heading, line no 2 Heading, line no 3 Identification of the run by alphanumerical text Always three input lines which may all be blank. Each line may contain up to 60 characters 2.1.3. Options and identifiers, one input line IRUNCO IANAL IDRIS IDENV IDSTAT IDIRR IDRES IRUNCO: character(4), default: DATA: Code for data check or executable run = FREM: Data generation for FREMOD = DATA: Data check = ANALysis: Analysis IANAL: character(4): Type of analysis to be performed = EIGEn: Eigenvalue analysis. Data section B must be given = REGUlar: Regular wave, time domain analysis. Data sections C and E must be given. = IRREgular: Irregular wave, time domain analysis. Data sections D and E must be given. IDRIS: character(6): Data set identifier corresponding to data for one riser system established by INPMOD and followed by a static analysis. See INPMOD: Data Group B: Single Riser Data and STAMOD: Options and print switches. IDENV: character(6): Environment identifier, corresponding to data for one environment on file established by INPMOD. See data-group INPMOD: Identification of the environment of input description for INPMOD. Reference to actual wave case is given in a later data-group Dummy for IRUNCO=DATAcheck IDSTAT: character(6): Static condition identifier, corresponding to data on file established by STAMOD. See STAMOD: Principal run parameters of input description for STAMOD. IDIRR: character(6): Data set identifier for irregular wave and motion data, either established by a previous run or used as reference to results stored on file by this run. IDRES: character(6): Data set identifier for this run, used as reference to results stored on files 2.2. Static load condition For special purposes it may be convenient to change applied static loads at the start of dynamic analysis. This option should be used with care! One useful application is for analysing free vibration after scaling a static nodal force to zero (SCALSF=0.0). Note that some static loads are applied and some modelling features are activated in dynamic analysis even if they were not applied nor activated in static analysis. See also Note: Static Analysis with Fixed Parameters and Parameter Variation. 2.2.1. Data group identifier, one input line STATic LOAD CONDition 2.2.2. Scaling parameters, one line SCALVF SCALSF SCALCF SCALVF: real, default: 1: Scaling of volume forces. Dummy not implemented in present version SCALSF: real, default: 1: Scaling of specified (nodal) forces SCALCF: real, default: 1: Scaling of current velocities. Dummy not implemented in present version All forces are scaled simultaneously as \(\mathrm {F_s=SCALiF\times F_s^0}\) Only SCALSF is active in the present version of the program. 2.3. Random number generator In version 4.18 and later, the algorithm for generating pseudo-random numbers may be selected by the user. The mersenne twister is the recommended method and should be used unless backwards compatibility with previous versions is required. Note that the default value may change in a future release. The choice of random number generator will apply to: generation of irregular wave time series initial phase angles for time domain VIV loads specified for cross-sections in INPMOD generation of phase angles for application of harmonic loads from a VIVANA frequency domain analysis. It has been identified that the legacy method can give non-gaussian and non-stationary wave elevation in SIMO for short crested waves with more than about 30-50 discrete directions, depending on wave spectrum and simulation duration. By choosing the mersenne twister, these issues are avoided. For coupled analysis, wave time series will be generated using the random number generator specified in SIMA. 2.3.1. Data group identifier, one input line RANDom NUMBer GENErator 2.3.2. Random number generator input, one line CHRAN ISEED CHRAN: character (7), default: TWISTER: Choice of random number generator = 'LEGACY': Legacy random number generator used. Results will be consistent with previous RIFLEX versions. = 'TWISTER': Mersenne Twister’ random number generator used. Results will NOT be consistent with previous RIFLEX versions. ISEED: integer, default: 7: Starting parameter of random number generator for use when input of starting value is not available; e.g. time domain VIV loads. Currently not used. 3. Data Group B: Free Vibration Analysis This data-group is given if and only if IANAL=EIGEn, see Options and indetifier, one input line. 3.1. Free vibration options 3.1.1. Data group identifier, one input line FREE VIBRation OPTIons 3.1.2. Number of eigenvalues and eigenvectors, one input line NEIG NEIG: integer: Number of eigenvalues and eigenvectors to be calculated. 3.1.3. Computation parameters, one input line The parameters below correspond to Lanczos’ method for solution of eigenvalue problems. For a detailed discussion, see B. Nour-Omid, B.N. Parlett, R.L. Taylor: Lanczos versus Subspace Iteration for Solution of Eigenvalue Problems, International Journal for Numerical Methods in Engineering, Vol. 19, pp. 859-871, 1983. or B.N. Parlett: The Symmetric Eigenvalue Problem, Prentice-Hall, 1980. TOL MAXLAN TOL: real >0, default: 1.0e-10: Maximum acceptable relative error in computed eigenvalues MAXLAN: integer, default: 8+2*NEIG: Maximum number of Lanczos steps (vectors) to be used. Note that if specified MAXLAN >= 8+2*NEIG 3.2. Print options for results 3.2.1. Data group identifier, one input line EIGEnvalue PRINt OPTIons 3.2.2. Print selection parameters, one input line This parameter is introduced to avoid very large dublicated amounts of result data to ASCII file IPRES IPRES: integer, default: 0: Print switch for eigenvectors on ASCII file <prefix>_dynmod.res/<prefix>_eigmod.res files. IPRES = 0: No print of eigenvector on ASCII file IPRES = 1: Print of eigenvectors on ASCII file IPRES = 2: Debug print from the eigenvalue solver in addition to print of eigenvectors on ASCII file 3.3. Termination of input data To terminate an input data stream, simply give the following, which is interpreted as a data group identifier. END Note that the END image cannot be omitted 4. Data Group C: Regular Wave, Time Domain Analysis This data group is given for IANAL = REGUlar, see Options and identifiers, one input line. Data-group A and E must also be given for complete definition of a regular time domain analysis. 4.1. Parameters for definition of analysis and further input 4.1.1. Data group identifier, one input line REGUlar WAVE ANALysis 4.1.2. Analysis parameters, one input line NPER NSTPPR IRWCN IMOTD NPER: integer: Number of periods for regular wave analysis, referring to wave or motion periods (of first vessel) NSTPPR: integer, default: 80: Number of integration time steps per period, recommended value: 50-120 IRWCN: integer: Wave parameter IRWCN = 0: No wave acting, motions must be present IRWCN = N: Wave acting. Regular wave case N on actual environment used in present analysis If no waves are acting, the period for harmonic motions is specified in Motion amplitudes of support vessel, one input line IMOTD: integer: Platform motion parameter IMOTD = 0: No motions, waves must be present IMOTD = 1: Platform motion generated on the basis of wave data (wave period and amplitude) and motion transfer functions. Reference to transfer functions given in Options and identifiers, one input line. IMOTD = 2: Platform motions specified in Regular vessel motion The platform motions are independent of the wave loading parameters given in Load modelling, regular waves. Extreme values of response parameters from last integration period will normally be stored on file (cfr. File storage of displacement response). In addition, displacement histories from selected nodes and force and curvature histories from selected elements can be stored if wanted. Specification of such data storage is given in data groups File storage of displacement response, File storage for internal force and File storage of curvature response. 4.2. Load modelling, regular waves This data group is given if IRWCN >= 1 (data group Analysis parameters, one input line above). 4.2.1. Data group identifier, one input line REGUlar WAVE LOADing 4.2.2. Method for wave load calculation, one input line IWTYP ISURF IUPPOS IWTYP: integer, default: 1: Wave theory parameter IWTYP = 1: Airy linear wave theory IWTYP = 2: Stoke 5th order wave theory ISURF: integer, default: 1: Sea surface definition, see the figure Definition of sea surface below. Dummy if IWTYP = 2 ISURF = 1: Integration of wave forces to mean water level ISURF = 2: Integration of wave forces to wave surface, deformation of potential by stretching and compression ISURF = 3: Integration of wave forces to wave surface, move of potential to actual surface ISURF = 4: Integration of wave forces to wave surface by keeping the potential constant from mean water level to wave surface IUPPOS: integer, default: 2: Riser position parameter IUPPOS = 0: as 1, but the riser is kept fixed in static position, for computation of surface penetrating element. I.e. a node that is wet or dry at the end of the static analysis will continue to be considered wet or dry with regards to kinematics in the dynamic simulation. Recommended only for comparison with linear methods. IUPPOS = 1: Wave induced velocities and accelerations calculated at static riser position IUPPOS = 2: Wave induced velocities and accelerations calculated at updated (dynamic) positions Note: The option IUPPOS = 0 cannot be combined with linear analysis, ITDMET = 1, or nonlinear analysis, ITDMET = 2 and SIMO bodies. Figure 1. Definition of sea surface 4.3. Regular vessel motion This data group is given only if IMOTD=2 (see input group Analysis parameters, one input line). 4.3.1. Data group identifier, one input line REGUlar VESSel MOTIon 4.3.2. Definition of vessel motion, two lines for each vessel Motion amplitudes of support vessel and Motion phase angles must be given for all NVES vessels in systems (totally 2x`NVES` lines). Motion amplitudes of support vessel, one input line Forced displacements are specified for the support vessel. Forced displacements for the terminal points are found by transformations. XAMP YAMP ZAMP XRAMP YRAMP ZRAMP PER XAMP: real: Motion amplitude, global x-direction \(\mathrm {[L]}\) YAMP: real: Motion amplitude, global y-direction \(\mathrm {[L]}\) ZAMP: real: Motion amplitude, global z-direction \(\mathrm {[L]}\) XRAMP: real: Motion amplitude, global x-rotation \(\mathrm {[degrees]}\) YRAMP: real: Motion amplitude, global y-rotation \(\mathrm {[degrees]}\) ZRAMP: real: Motion amplitude, global z-rotation \(\mathrm {[degrees]}\) PER: real: Period of motion \(\mathrm {[T]}\) PER is dummy input if a regular wave is specified, i.e. IRWCN > 0 (data group Analysis parameters). In the case of multiple vessels, PER is only read for the first vessel and the specified period used for all vessels. Motion phase angles, one input line XPHA YPHA ZPHA XRPHA YRPHA ZRPHA XPHA: real: Phase angle, x-motion \(\mathrm {[degrees]}\) YPHA: real: Phase angle, y-motion \(\mathrm {[degrees]}\) ZPHA: real: Phase angle, z-motion \(\mathrm {[degrees]}\) XRPHA: real: Phase angle, x-rotation \(\mathrm {[degrees]}\) YRPHA: real: Phase angle, y-rotation \(\mathrm {[degrees]}\) ZRPHA: real: Phase angle, z-rotation \(\mathrm {[degrees]}\) All phase angles are defined as follows: Positive angle: Forward phase shift; motion before sea surface at global origin. Surface: \(\mathrm {\eta =\eta _asin(\omega t+\phi _p),\quad \phi _p=-kxcos(\beta )-kysin(\beta )}\) Motion: \(\mathrm {x_i=x_{ai}sin(\omega t+\phi _i)}\) Where: \(\mathrm {x_i}\) is equation of motion \(\mathrm {\eta _a}\) is wave amplitude \(\mathrm {x_{ai}}\) is motion amplitude XAMP, YAMP, etc. \(\mathrm {\phi _i}\) is phase angle, XPHA, YPHA, etc. \(\mathrm {k}\) is wave number \(\mathrm {\omega }\) is angular frequency \(\mathrm {x,y}\) is global coordinates If the forward phase shift \(\mathrm {\phi _i^{xy}}\) between wave and motion at the same point (x,y) is known, the phase into RIFLEX must be modified as follows: \(\mathrm {\phi _i=\phi _i^{xy}+\phi _p}\) in order to obtain phase relation between motion at (x,y) and a wave with start at global origin as defined above. 5. Data Group D: Irregular Wave, Time Domain Analysis This data group is given for IANAL=IRREgular, see Options and identifiers, one input line. Data group A and E must also be given for complete definition of an irregular time domain analysis. 5.1. Irregular time series parameters The input in this data group is used to specify the method used for computation of the underlaying irregular waves, i.e. the seed used for random number generation and the frequency resolution. The data group may be skipped if default values are wanted. The data group is dummy if any floater force models are present in the model. (The analysis is done in combination with SIMO, so-called coupled analysis, and the irregular time series parameters defined by input to SIMO). 5.1.1. Data group identifier, one input line IRREgular TIMEseries PARAmeters 5.1.2. Parameters, one input line IRAND TIMGEN DTGEN CHFREQ CHAMP IRAND: integer, default: 1: Starting parameter of random number generator TIMGEN: real, defaul: 16384: Length of prescribed wave and motion time series \(\mathrm {[T]}\) DTGEN: real, defaul: 0.5: Time increment of pre-sampled time series \(\mathrm {[T]}\) CHFREQ: character(4), default: FFT: Option for selecting wave frequency components = 'FFT': Wave frequency components are selected among the FFT frequencies given by TIMEGEN and DTGEN. The default criteria are used to find the first and last frequencies. CHAMP: character(5), default: DET: Option for selecting wave component amplitudes = 'DET': Deterministic wave amplitudes are used. = 'STOCH': Stochastic wave amplitudes are used. = 0: Interpreted as DET. Included for compatibility with earlier versions. Note that this data group is dummy for coupled analysis. Also note that: TIMGEN should be equal or longer than the simulation length, TIME, given in Irregular response analysis and subsequent input. TIMGEN will, if necessary, be increased to give a power of 2 time steps (DTGEN). The actual time increment used for time domain analysis is defined by the parameter DT, see Irregular response analysis and subsequent input. To represent the wave surface- and motion time series properly, time increments, DTGEN, in the range 0.5-1 s are normally acceptable. Time series of wave elevation are generated from the wave spectrum for simulations with irregular waves. Different wave seeds will result in different wave time series. The wave time series are realizations of the wave process described by the wave spectrum. With deterministic amplitudes, the amplitude pf each wave component is given directly by the wave spectrum and will be the same for all realizations. The phase angles of the different wave components will vary between realizations, resulting in different wave time series. The wave time series will all have the same spectrum, identical to the original wave spectrum at the frequencies of the wave components. With stochastic amplitudes, the amplitude for each wave component will also be varied around the value of the wave spectrum. The spectra of the generated wave time series will vary between realizations and will not be the same as the original wave spectrum. Using stochastic amplitudes will normally give more variation between the results for different wave seeds. 5.2. Irregular response analysis and subsequent input 5.2.1. Data group identifier, one input line IRREgular RESPonse ANALysis 5.2.2. Analysis parameters, one input line IRCNO TIME DT CHWAV CHMOT CHLFM TBEG ISCALE IRCNO: integer/character: Irregular wave case number in actual environment applied in this run. Dummy for coupled analysis. IRCNO = FILE or IRCNO = -1: Wave time series read from file. Data groups Irregular waves and Wave time series file must be given TIME: real, default: 11000: Length of simulation \(\mathrm {[T]}\) DT: real, default: 0.1: Time step \(\mathrm {[T]}\) See below CHWAV: character(4), default: NEW: Irregular wave indicator = 'NONE': No wave forces in present analysis. If specified the riser will have forced excitation at upper end and oscillate in undisturbed water or in constant current = NEW: Wave forces present. New data generated. Data group Irregular waves must be given. CHMOT: character(4), default: STAT: Irregular motion indicator = 'NONE': No irregular motions in present analysis = STAT: Forced irregular motions present. Computation of prescribed motions will be based on vessel position in final static position. = NEW: Interpreted as CHMOT=STAT = FILE: Forced irregular motions present. Wave frequency motion time series read from file. Data group Wave frequency motion time series file must be given. CHLFM: character(4), default: 'NONE': Low frequency motion indicator = 'NONE': No low frequency irregular motions present = FILE: Forced low frequency irregular motions present. Low frequency motion time series read from file. Data group Low frequency motion time series file must be given. TBEG: real, default: 0: Time in wave and motion time series that dynamic simulation will start from \(\mathrm {[T]}\) ISCALE: integer, default: 0: Switch for scaling of terminal point motions ISCALE = 0: No scaling ISCALE = 1: Scaling: Input line Support vessel motion scaling factors has to be given. DT will be adjusted to get an integer ratio between DTGEN and DT. DT given as negative integer defines the ratio between time step used in pre-simulation of waves and/or WF-motions and the time step to be used in the time simulation. (DTGEN/DT >= 1) TBEG allows for arbitrary start point in the pre-generated time series. If the end of the time series is reached during dynamic integration, a warning is written and motions and water kinematics will be taken from the start. This can also be useful for elimination of transients from the time series statistics. An irregular analysis without waves or vessel motions may be run by specifying CHWAV = 'NONE', CHMOT = 'NONE' and CHLFM = 'NONE'. IRCNO must still reference a legal irregular wave case, but the wave will not be used as no wave kinematics will be generated and not vessel motions be applied. 5.2.3. Support vessel motion scaling factors. Only given for ISCALE=1. One line for each vessel in system (NVES lines) SCALX SCALY SCALZ SCALXR SCALYR SCALZR SCALX: real, default: 1: Scaling for global X-motion \(\mathrm {[1]}\) SCALY: real, default: 1: Scaling for global Y-motion \(\mathrm {[1]}\) SCALZ: real, default: 1: Scaling for global Z-motion \(\mathrm {[1]}\) SCALXR: real, default: 1: Scaling for global X-rotation \(\mathrm {[1]}\) SCALYR: real, default: 1: Scaling for global Y-rotation \(\mathrm {[1]}\) SCALZR: real, default: 1: Scaling for global Z-rotation \(\mathrm {[1]}\) The motions are scaled directly as \(\mathrm {DISP_i=SCAL_i\times Motion_i}\) where \(\mathrm {Motion_i}\) is the precomputed motion quantity \(\mathrm {_i}\). 5.3. Irregular waves This data group is omitted for CHWAV='NONE', see data group Analysis parameters, one input line. The data group also controls the method for computation of wave kinematics and motions of the support vessels. In this context FFT or FFT and cosine series combined means that the vessel motion is pre-generated by means of FFT, while the wave kinematics are either pre-generated (FFT) or computed during the actual simulation by use of cosine series. Cosine series only means that both vessel motion and wave kinematics are computed based on cosine series. It is possible to overrule the cosine series application for wave kinematics for parts of the the system by specifying FFT in the detailed specifications, see Additional detailed specification of wave kinematics points (optional). (FFT or FFT and cosine series combined only.) 5.3.1. Data group identifier, one input line IRREgular WAVE PROCedure 5.3.2. Procedure for wave force calculation, one input line IUPPOS ISURF KINOFF CHSTEP NODSTP ZLOWER ZUPPER IOPDIF IOPWKI IUPPOS: integer, default: 1: Position for calculation of irregular wave kinematics = 1: Kinematics at static positions = 2: Kinematics at instantaneous positions calculated by summation of cosine components. = -2: Kinematics at static positions calculated by summation of cosine components. This option is mainly useful for testing. = 0: As 1 but riser fixed in static position, (wet elements also wet dynamic) ISURF: integer, default: 1: Code for kinematics in wave zone = 1: Integration of wave forces to mean water level = 2: Integration of wave forces to wave surface by stretching and compression of the wave potential = 3: Integration of wave forces to wave surface by moving the potential to actual surface = 4: Integration of wave forces to wave surface by keeping the potential constant from mean water level to wave surface = 5: 2nd order wave (integration of wave forces to wave surface) The formulation for 2nd order wave kinematics is based on the Stoke 2nd order wave theory. Only available for kinematics calculated at static position; IUPPOS = 1 or IUPPOS = 0. KINOFF: integer, default: 0: Code for default kinematics points procedure = 0: Default procedure on. The initial selection of positions for computation of kinematics is determined by the parameters NODSTP, ZLOWER and ZUPPER for all lines in the system. Subsequent specification (see Additional detailed specification of wave kinematics points (optional)) will replace the initial selection. = 1: Default procedure off. Kinematics will only be computed at positions given by subsequent specification (see Additional detailed specification of wave kinematics points (optional)) CHSTEP: character(4): Code for interpretation of the next parameter = NODE: Next parameter interpreted as NODSTP NODSTP: integer: Node step for calculating wave kinematics. (Dummy for KINOFF = 1) Kinematics calculated for every NODSTP node between ZLOWER and ZUPPER (see Definition of NODSTP, ZLOWER and ZUPPER). For intermediate nodes kinematics are derived by linear interpolation. Wave kinematics will always be calculated at submerged supernodes. Note that a negative value of NODSTP may be given. The distance between ZUPPER and ZLOWER is then divided into 4 (equal) intervals and NODSTP is increased from ABS(NODSTP) in the upper interval via 2xABS(NODSTP) in the next interval and 4xABS(NODSTP) to 8xABS(NODSTP) in the two lower intervals, see Definition of NODSTP, ZLOWER and ZUPPER. ZLOWER: real, default: -WDEPTH: Z-coordinate indicating lowest node position for which wave kinematics are calculated \(\mathrm {[L]}\) See Definition of NODSTP, ZLOWER and ZUPPER. Dummy for KINOFF = 1 For WDEPTH, see INPMOD: Water depth and wave indicator ZUPPER: real, default: 4 x STD_WA: Upper limit for wave kinematics \(\mathrm {[L]}\) Dummy for KINOFF = 1 STD_WA is the standard deviation of the total wave elevation IOPDIF: integer, default: 0: Option for specification of wave kinematic transfer function. IOPDIF = 0: No transfer function to be specified IOPDIF = 1: Read transfer functions from the file specified in Wave kinematics transfer function file name (below). IOPWKI: integer, default: 0: Option for specification of wave kinematic time series. IOPWKI = 0: No wave kinematics time series to be specified IOPWKI = 2: Read wave kinematics time series from the binary file specified in Wave kinematics transfer function file name (below). NODSTP, ZLOWER and ZUPPER will normally be sufficient for specifying the selection of wave kinematics points. Note that for large or complicated systems Additional detailed specification of wave kinematics points (optional) may be used to override the selection given by NODSTP, ZLOWER and ZUPPER; e.g. skip generation of wave kinematics for selected lines, generate kinematics at more points along an important line. Figure 2. Definition of NODSTP, ZLOWER and ZUPPER Note that the definition of ISURF is also used to determine where to apply wind forces to airfoil cross sections near the water line. That is, no wind forces are applied to wet sections of the element. The wind speed is nevertheless taken to be zero at or below the mean water level. Note that the option IUPPOS = 0 cannot be combined with linear analysis, ITDMET = 1, or nonlinear analysis, ITDMET = 2 and SIMO bodies. Wave kinematics transfer function file name This data group is omitted for IOPDIF = 0 CHFDIF CHFDIF: character(80): File name with wave kinematic transfer function. The file format is described in Diffracted Wave Transfer Functions at Points. Wave kinematics time series file name This data group is omitted for IOPWKI = 0 Wave kinematics read from file will replace the corresponding wave kinematics calculated by DYNMOD. These kinematics will then be used in the calculation of Morison type hydrodynamic loads on RIFLEX elements. Loads on SIMO bodies will NOT be affected. RIFLEX vessel motions based on vessel motion transfer functions and MacCamy Fuchs and Potential flow loads on RIFLEX elements are per-generated from the wave Fourier components and are therefore NOT affected by the wave kinematics read from file. Elements with MacCamy Fuchs or Potential flow loads may not have kinematics read from file. If kinematics read from file are used in a simulation with SIMO bodies, vessel motions based on vessel motion transfer functions or pre-generated hydrodynamic loads, the user must ensure that the kinematics are consistent with the Fourier components. CHFWKI CHFWKI: character(80): File name with wave kinematic time series. The file format is specified by IOPWKI and is the same as the kinematics file with the same format exported from DYNMOD using Storage of irregular wave kinematics ICOLMX ICOLTM NQNTWK ICOLMX: integer, default: 0: Maximum number of columns on file. For binary format, IOPWKI = 2, this includes the two columns of FORTRAN specific data, one column for time and NQNTWK columns for each node for which kinematics are stored on this file; i.e. 3 + NQNTWK * n. Please see the key file key_<prefix>_wavkin.txt generated when storing kinematics. ICOLTM: integer, default: 2: Column number on file for time NQNTWK: integer, default: 0`: Number of kinematics quantities on the file for each kinematic node. NQNTWK =7: Wave elevation, x-velocity, y-velocity, z-velocity, x-acceleration, y-acceleration and z-acceleration are read for each specified node NQNTWK = 8: Wave elevation, x-velocity, y-velocity, z-velocity, x-acceleration, y-acceleration, z-acceleration and dynamic pressure are read for each specified node NQNTWK =0: The value of NQUANT will be found from the specified column numbers. Additional detailed specification of wave kinematics points (optional) As many input lines as needed. Note three alternative formats. For wave kinematics calculated by the program from the undisturbed waves. LINE-ID CHSTEP = NODE NODSTP LINE-ID: character(8): Line identifier CHSTEP: character(4): = Node NODSTP: integer: Node step for calculating wave kinematics = 0: No kinematics for this line > 0: Kinematics for each NODSTP node For wave kinematics given by wave kinematics transfer functions (diffracted waves) LINE-ID CHSTEP= DIFF ILSEG ILNODE IVES PTNOUS LINE-ID: character(8): Line identifier CHSTEP: character(4): = DIFF ILSEG: integer: Local segment number within line LINE-ID ILNODE: integer: Local node number within ILSEG IVES: integer: = 0: Use undisturbed wave kinematics at this node > 0: Support vessel number. Used as reference to transfer function for diffracted wave kinematics. PTNOUS: integer: Point reference(s) to transfer function for diffracted wave kinematics Up to 30 values of PTNOUS may be given for a node. The diffracted kinematics at the specified node will be generated by interpolation based on the nearest point references. For wave kinematics given by wave kinematics time series LINE-ID CHSTEP= WKFI ILSEG ILNODE ICOLST LINE-ID: character(8): Line identifier CHSTEP: character(4): = WKFI ILSEG: integer: Local segment number within line LINE-ID ILNODE: integer: Local node number within ILSEG ICOLST: integer: Column number for the first wave kinematics time series for this node 5.4. Wave and motion time series files 5.4.1. Wave time series file This data group is given only if IRCNO = FILE. Data group identifier, one input line WAVE TIME SERIes Wave time series file information CHFTSF IFORM ICOTIM ICOWAV CHFTSF: character(60): File name IFORM: integer, default: 1: File format code = ASCI: Column organised ASCII file = STAR: Startimes file ICOTIM: integer, default: 1: Column number for time Dummy for IFORM = STAR ICOWAV: integer/real, default: 2: Column or time series number for wave elevation The wave direction is given by the parameter WADR1 given in INPMOD for the irregular wave case IRCNO referred to in Analysis parameters, one input line.. ICOTIM and ICOWAV will refer to columns on an ASCII file; e.g. ICOTIM=1 and ICOWAV=2 if the time and wave elevation are in the first and second columns; or to a time series number on a Startimes file; e.g. ICOWAV=10.01 for time series 10, version 1. An arbitrary time step may be used on an ASCII file, while the Startimes file has a fixed step. Linear interpolation is used to get the motions at the time step (DTWF) Direction, location of measurement and cut-off for filtering WAVDIR XGWAV YGWAV TMIN TMAX WAVDIR: real, default: 0: Wave direction \(\mathrm {[deg]}\) XGWAV: real, default: 0: Global x-coordinate for position where time series is measured YGWAV: real, default: 0: Global y-coordinate for position where time series is measured TMIN: real, default: 0: Period corresponding to cut-off frequency for filtering TMAX: real, default: 0: Period corresponding to cut-off frequency for filtering If TMIN and TMAX are both zero: No filtering If TMIN and TMAX are both different from zero: band-pass filtering Filtering is not implemented in present version 5.4.2. Wave frequency motion time series file This data group is given only if CHMOT=FILE. Note that data must be given for all vessels in the system. Data group identifier, one input line WFMOtion TIME SERIes Wave frequency motions file information, NVES input lines IVES CHFTSF IFORM IKIND IROT ICOTIM ICOXG ICOYG ICOZG ICOXGR ICOYGR ICOZGR IVES: integer: Vessel Number CHFTSF: character(60): File name IFORM: character(4), default: ASCI: File format code = ASCI: Column organised ASCII file = STAR: Startimes file = NONE: No wave frequency motions for this vessel. The remainder of this input line is dummy IKIND: character(4), default: POSI: Kind of motion time series input = POSI: Global positions, i.e. global coordinates. The rotations are applied in the Euler sequence: Rz-Ry-Rx. Consistent with vessel motion time series from SIMO. = DYND: Global dynamic displacements; i.e. global coordinates minus the final static position. The rotations are applied in the Euler sequence: Rx-Ry-Rz IROT: character(4), default: DEGR: Unit of rotations = DEGR: Rotations given in degrees = RADI: Rotations given in radians ICOTIM: integer, default: 1: Column number for time Dummy for IFORM = STAR ICOXG: integer/real, default: 0: Column or time series number for specification of global x-motion. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOYG: integer/real, default: 0: Column or time series number for specification of global y-motion. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOZG: integer/real, default: 0: Column or time series number for specification of global z-motion. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOXGR: integer/real, default: 0: Column or time series number for specification of global x-rotation. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOYGR: integer/real, default: 0: Column or time series number for specification of global y-rotation. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOZGR: integer/real, default: 0: Column or time series number for specification of global z-rotation. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. Dofs may be omitted by giving ICOxxx=0 ICOxxx will refer to a column for an ASCII file; e.g. ICOX=2 if the dynamic x motion time series is in the second column; or to a time series number for a Startimes file, e.g. ICOX=1.02 for time series 1, version 2. An arbitrary time step may be used on an ASCII file, while the Startimes file has a fixed time step. Linear interpolation is used to get the motions at the time step (DTWF). Translational dofs are given in length units. Rotational dofs are given in degrees or radians, depending on the option IROT. If only one rotation is nonzero or if all rotations are small, the order in which the rotations are applied will not be significant. Please note that the line length of ASCII input files is currently limited to 260 characters, see Formats in How to Run the Program. Note that a RIFLEX input line may be split into several lines on the input file. 5.4.3. Low frequency motion time series file This data group is given only if CHLFM=FILE. Note that data must be given for all vessels in the system. Data group identifier, one input line LFMOtion TIME SERIes Low frequency motions file information, NVES input lines IVES CHFTSF IFORM IKIND IROT ICOTIM ICOXG ICOYG ICOZGR IVES: integer: Vessel Number CHFTSF: character(60): File name IFORM: character(4), default: ASCI: File format code = ASCI: Column organised ASCII file = STAR: Startimes file = NONE: No wave frequency motions for this vessel. The remainder of this input line is dummy IKIND: character(4), default: POSI: Kind of motion time series input = POSI: Global positions, i.e. global coordinates. The rotations are applied in the Euler sequence: Rz-Ry-Rx. Consistent with vessel motion time series from SIMO. = DYND: Global dynamic displacements; i.e. global coordinates minus the final static position. The rotations are applied in the Euler sequence: Rx-Ry-Rz IROT: character(4), default: DEGR: Unit of rotations = DEGR: Rotations given in degrees = RADI: Rotations given in radians ICOTIM: integer, default: 1: Column number for time Dummy for IFORM = STAR ICOXG: integer/real, default: 0: Column or time series number for specification of global x-motion. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOYG: integer/real, default: 0: Column or time series number for specification of global y-motion. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. ICOZGR: integer/real, default: 0: Column or time series number for specification of global z-rotation. Absolute position if IKIND = POSI, relative to static position if IKIND = DYND. Dofs may be omitted by given ICOxxx=0 ICOxxx will refer to a column for an ASCII file; e.g. ICOSUR=2 if the dynamic x motion time series is in the second column; or to a time series number for a Startimes file, e.g. ICOX=1.02 for time series 1, version 2. An arbitrary time step may be used on an ASCII file, while the Startimes file has a fixed time step. Linear interpolation is used to get the motions at the time step (DTWF). Translational dofs are given in length units. Rotational dofs are given in degrees or radians, depending on the option IROT. If only one rotation is nonzero or if all rotations are small, the order in which the rotations are applied will not be significant. 5.5. Print options for FFT analysis 5.5.1. Data group identifier, one input line IRREgular FOURier PRINt 5.5.2. Fourier print options IPMOTI IPWAFO IPHFTS IPLFTS IPTOMO IPVEAC IPMOTI: integer, default: 0: Print option for the main routine ⇐ 0: No print > 1: Key information printed > 2: Some more data printed > 5: Low level debug print during numerical integration activated IPWAFO: integer, default: 0: Print option for the wave fourier component generation Not active in present version IPHFTS: integer, default: 0: Print option for HF-time series generation ⇐ 0: No print > 0: Print of wave frequency vessel motion time series IPLFTS: integer, default: 0: Print option for LF-time series generation ⇐ 0: No print > 0: Print of low frequency vessel motion time series IPTOMO: integer, default: 0: Print option for TOTAL motion time series generation ⇐ 0: No print > 0: Print of total vessel motion time series IPVEAC: integer, default: 0: Print option for generation of water particle velocities and acceleration ⇐ 0: No print > 1: Key information printed > 2: Some data printed > 5: Extensive debug print of arrays with water particle velocities and accelerations This data-group is normally supposed to be omitted. Increasing value of print options gives increasing amount of print. 5.6. Storage of irregular wave kinematics (optional) 5.6.1. Data group identifier, one input line IRREgular KINEmatics STORage 5.6.2. Wave kinematics storage options one input line NLKINE IKINFM NLKINE: integer, default: 0: Number of specifications for storage of wave kinematics = 0: Wave elevation, velocities, accelerations and pressure are stored for all kinematics nodes. Currently, no other value is allowed. IKINFM: integer, default: 2: File format for kinematics storage = 1: ASCII format = 2: Binary format Pre-generated wave kinematics are written to <prefix>_wavkin.asc or <prefix>_wavkin.bin. Kinematics calculated during the simulation; IUPPOS = 2 or -2; are written to <prefix>_updkin.asc or <prefix>_updkin.bin. The contents are described in key_<prefix>_wavkin.txt or key_<prefix>_updkin.txt. The format of the <prefix>_wavkin.bin and <prefix>_updkin.bin are shown in Table 1. Table 1 shows storage of data for M number of time steps and N number of kinematic nodes.The data is stored row by row. The number of columns is equal to 3+8N. The first and last columns contain the number of bytes per line ( i.e. number of bytes = 4(8N+1) ). The second column is the time step. The numbers are stored as 32bit (4byte) floating point number, except the first and last column which is 4 byte unsigned integer. The disk consumption is equal to 4M(3+8N) bytes. The number of kinematics quatities in the file generated by Riflex is 8. That is the wave elevation, x-velocity, y-velocity, z-velocity, x-acceleration, y-acceleration, z-acceleration and dynamic pressure are stored for each specified node. Table 1. Format of wave kinematics binary file <prefix>_wavkin.bin and <prefix>_updkin.bin. Column no=1 2 3 to 10 11 to 18 19 to 26 … 3+(N-1)8 to 2+8N 3+8N time Node1 Node2 Node3 … NodeN 4(8N+1) t1 wave(t1,x1) wave(t1,x2) wave(t1,x3) … wave(t1,xN) 4(8N+1) 4(8N+1) t2 wave(t2,x1) wave(t2,x2) wave(t2,x3) … wave(t2,xN) 4(8N+1) 4(8N+1) t3 wave(t3,x1) wave(t3,x2) wave(t3,x3) … wave(t3,xN) 4(8N+1) … … … … … … … 4(8N+1) tM wave(tM,x1) wave(tM,x2) wave(tM,x3) … wave(tM,xN) 4(8N+1) A list of the kinematic nodes can be found on the <prefix>_dynmod.res-file. If the kinematic binary file is generated by an external tool and used as input to Riflex, Section 5.3.2.2, the number of kinematics quatities can be 7 (wave elevation, x-velocity, y-velocity, z-velocity, x-acceleration, y-acceleration and z-acceleration). 6. Data Group E: Time Domain Procedure and File Storage Parameters This data group must always be given for IANAL = REGU and IRRE (time domain analysis) specified in input line Options and identifiers, one input line. 6.1. Method of analysis and subsequent input 6.1.1. Data group identifier, one input line TIME DOMAin PROCedure 6.1.2. Method and subsequent input, one input line ITDMET INEWIL ITDMET: integer, default: 1: Method indicator ITDMET = 0: Prestochastic analysis only. The rest of the data in input groups E are irrelevant ITDMET = 1: Linear analysis ITDMET = 2: Nonlinear analysis. More information to define method is given in Nonlinear step by step integration INEWIL: integer, default: 1: Procedure indicator INEWIL = 1: Newmark’s procedure INEWIL = 2: Wilson’s procedure, illegal for non-linear analysis 6.1.3. Time integration and damping parameters, one input line This data group can be omitted if default values are wanted. BETIN GAMMA TETHA A1 A2 A1T A1TO A1B A2T A2TO A2B DAMP_OPT BETIN: real, default: 4/6: Inverse value of beta-parameter of the Newmark beta-family of integration operators BETIN = 4.0 gives beta=1/4,i.e. constant average acceleration method GAMMA: real, default: 0.5: Value of the parameter gamma of the Newmark operators (usually equal to 0.5) TETHA: real, default: See below: Value of the parameter tetha in Wilson’s integration method A1: real, default: 0: Global mass proportional damping factor \(\mathrm {a_1}\), see definition below A2: real, default: 0.001/0: Global stiffness proportional damping factor \(\mathrm {a_2}\) A1T: real, default: 0: Additional local mass proportional damping factor \(\mathrm {a_{1t}}\) for tension A1TO: real, default: 0: Additional local mass proportional damping factor \(\mathrm {a_{1to}}\) for torsion A1B: real, default: 0: Additional local mass proportional damping \(\mathrm {a_{1b}}\) for bending A2T: real, default: 0: Additional local stiffness proportional damping factor \(\mathrm {a_{2t}}\) for tension A2TO: real, default: 0: Additional local stiffness proportional damping factor \(\mathrm {a_{2to}}\) for torsion A2B: real, default: 0: Additional local stiffness proportional damping factor \(\mathrm {a_{2b}}\) for bending DAMP_OPT: character(4), default: TOTA: Option for stiffness contribution to Rayleigh damping = TOTA: Stiffness proportional damping is applied using total stiffness, i.e. both material and geometric stiffness = MATE: Stiffness proportional damping is applied using material stiffness only Default values: For INEWIL=1 (Newmark) the following alternative default values are: BETIN=4.0, THETA=1.0, A2=0.001 For INEWIL=2 (Wilson) default values are: BETIN=6.0, TETHA=1.4 (linear) Global proportional damping formulation: \(\mathrm {\boldsymbol{\mathrm C}=a_1\boldsymbol{\mathrm M}+a_2\boldsymbol{\mathrm K}}\) This means that the global damping matrix \(\mathrm {\boldsymbol{\mathrm C}}\) is established as a linear combination of the global mass (\(\mathrm {\boldsymbol{\mathrm M}}\)) and the total or material stiffness (\(\mathrm {\boldsymbol{\mathrm K}}\)) matrices. The mass and stiffness-proportional damping specified here will not be applied to elements for which mass- and/or stiffness-proportional damping is specified in INPMOD. Numerical values of \(\mathrm {a_1}\) and \(\mathrm {a_2}\): Let the structural damping to critical damping ratio, \(\mathrm {c/(2m\omega )}\), at two natural frequencies \(\mathrm {\omega _1}\) and \(\mathrm {\omega _2}\) be \(\mathrm {\lambda_1}\) and \(\mathrm {\lambda_2}\), respectively. Then A1 and A2 can be computed as: - \(\mathrm {a_1=\frac{2\omega _1\omega _2}{\omega _2^2-\omega _1^2}(\lambda_1\omega _2-\lambda_2\omega _1)}\) - \(\mathrm {a_2=\frac{2(\omega _2\lambda_2-\omega _1\lambda_1)}{\omega _2^2-\omega _1^2}}\) Additional local proportional damping formulation: In this approach, the damping coefficients are introduced in the local degrees of freedom in order to allow for different damping levels in bending, torsion and tension. The element damping matrix can the be written as \(\mathrm {\boldsymbol{\mathrm c}=a_1\boldsymbol{\mathrm M}+a_{1t}\boldsymbol{\mathrm m}_t+a_{1to}\boldsymbol{\mathrm m}_{to}+a_{1b}\boldsymbol{\mathrm m}_b+a_2\boldsymbol{\mathrm K}+a_{2t}\boldsymbol{\mathrm k}_t+a_{2to}\boldsymbol{\mathrm k}_{to}+a_{2b}\boldsymbol{\mathrm k}_{b}}\) where subscripts \(\mathrm {_t}\), \(\mathrm {_{to}}\) and \(\mathrm {_b}\) refer to tension, torsion and bending contributions, respectively, and the matrices \(\boldsymbol{\mathrm c_{}}\), \(\boldsymbol{\mathrm m}\) and \(\boldsymbol{\mathrm k_{}}\) are local element matrices; e.g. \(\mathrm {\boldsymbol{\mathrm k}_b}\) includes all bending deformation terms in the local element stiffness matrix. For cross sections applied for blades of a operating wind turbine the matrix \(\boldsymbol{\mathrm k_{}}\) should only include the material stiffness matrix. The geometric stiffness matrix should not be included as this would introduce damping of the rigid body motion. One should be careful with global mass proportional damping as this may introduce internal damping from rigid body motion. If \(\mathrm {a_1=}\) 0, \(\mathrm {a_2}\) simply becomes \(\mathrm {2\lambda/\omega }\). Note that proportional damping (global and local) adds to a possible structural damping arising from hysteresis in bending moment/curvature relation. 6.1.4. Non-linear force model, one input line. Always submit for linear and non-linear analysis INDINT INDHYD MAXHIT EPSHYD TRAMP INDREL ICONRE ISTEPR LDAMP INDINT: integer, default: 1: Indicator for modelling forces from internal slug flow Nonlinear analysis only. INDINT = 1: Forces from internal slug flow not considered INDINT = 2: Forces from internal slug flow considered. Data group Slug force calculations or Import of internal flow data from file must be given. INDHYD: integer, default: 1: Indicator for hydrodynamic force model. Linear analysis only. (see Dynamic Time Domain Analysis in the Theory Manual). INDHYD = 1: No force iteration, use of displacements and velocities at previous time step INDHYD = 2: No force iteration, use of displacements, velocities and accelerations at previous time step (not recommended) INDHYD = 3: Force iteration performed MAXHIT: integer, default: 5: Maximum number of load iterations. Linear analysis only. A negative value gives print of convergence for each step, then MAXHIT = ABS(MAXHIT) EPSHYD: real, default: 0.01: Convergence control parameter for force iteration. Linear analysis only. Dummy for INDHYD = 1, 2 \(\mathrm {[1]}\) TRAMP: real, default: 10: Duration of start-up procedure \(\mathrm {[T]}\) INDREL: integer, default: 0: Indicator for rupture/release INDREL = 0: No riser rupture/release INDREL = 1: Riser rupture/release will be simulated ICONRE: integer, default: 0: Ball joint connector no. to be released ICONRE = 0: All ball joint connectors in the system are released simultaneously ICONRE = i: Ball joint connector no. i is released. See reference number ("ref no") in the table Components on the STAMOD result file for connector numbering. The connectors are normally numbered from the first end as 1, 2 etc. following the FEM model. ISTEPR: integer, default: 0: Time step no. for release (nonlinear analysis only) In linear analysis the ball joint connector will be released at the first step LDAMP: integer, default: 0: Option for calculation of proportional damping matrix in nonlinear analysis. Irrelevant for linear analyses LDAMP = 0: Use constant proportional damping matrix calculated at static position LDAMP = 1: Use updated proportional damping matrix according to instantaneous mass and stiffness matrices For non-linear analysis (ITDMET = 2, see Method and subsequent input, one input line) INDHYD can have the values 1 or 2. Input of 3 will be interpreted as 2. Load iteration for non-linear analysis will always be performed in connection with equilibrium iteration, but not during equilibrium correction. If load convergence is not obtained after MAXHIT iteration, computation will proceed after output of warning. As a release/rupture analysis is very sensitive, a short time step and rather firm convergence limit is required. If the response of part of the system is not of interest after the release, the Boundary change option may be used to fix the nodes in this part of the system. Figure 3. Definition of clutch (start up procedure) 6.2. Nonlinear step by step integration This data group is only given for ITDMET=2 (input group Method and subsequent input, one input line).). 6.2.1. Data group identifier, one input line NONLinear INTEgration PROCedure 6.2.2. Specification of incrementation procedure, one input line ITFREQ ISOLIT MAXIT DACCU ICOCOD IVARST ITSTAT CHNORM EACCU ITFREQ: integer, default: 1: Frequency of equilibrium iteration ITFREQ ⇐ 0: Iteration will not be performed ITFREQ >= 1: Iteration will be performed every ITFREQ time step. For steps without iteration equilibrium correction will be performed. The remaining variables in this input line are dummy if ITFREQ ⇐ 0 ISOLIT: integer, default: 1: Type of iteration if iteration is to be performed ISOLIT = 1: True Newton-Raphson, updating of geometric stiffness from axial force ISOLIT = 2: Modified Newton-Raphson iteration Modified Newton-Raphson iteration is not included in the current version of the program MAXIT: integer, default: 10: Maximum number of iterations for steps with iteration DACCU: real, default: \(\mathrm {10^{-6}}\): Desired accuracy for equilibrium iteration measured by a modified Euclidean displacement norm (norm of squared translations) Recommended values: \(\mathrm {10^{-6}-10^{-5}}\) cfr. STAMOD analysis \(\mathrm {[1]}\) ICOCOD: integer, default: 1: Code for continuation after iteration ICOCOD = 0: Computations interrupted if accuracy requirements are not fulfilled ICOCOD = 1: Computations continue even if accuracy requirements are not fulfilled. Warning is printed IVARST: integer, default: 0: Code for automatic subdivision of time step IVARST = 0: No subdivision IVARST > 0: Automatic subdivision of time step if required accuracy is not obtained with original time step or if incremental rotations are to large. Maximum number of subdivisions: \(\mathrm {2^{IVARST}}\) ISTAT: integer, default: 1: Code for time integration information ITSTAT = 0: No information ITSTAT > 1: Number of iterations, subdivisions and obtained accuracy are presented CHNORM: character(4), default: DISP: Convergence norm switch = DISP: Use the default Euclidean displacement norm only = BOTH: Use both the default Euclidean displacement norm and the energy norm EACCU: real, default: \(\mathrm {10^{-6}}\): Required accuracy measured by energy norm Dummy if CHNORM=DISP 6.3. Modification to water kinematics Modification to water kinematics due to moonpool kinematics may be specified. The water kinematics will be based on the velocities and acceleration of the actual support vessel or floater force model specified. 6.3.1. Data group identifier, one input line WATEr KINEmatic CONDition 6.3.2. Rigid moonpool column, one input line RIGId MOONpool COLumn Specification of number of moonpools, one input line NLSPEC NLSPEC: integer: Number of Rigid Moonpool Columns Specification of support vessel moonpool, one input line. CHSUPP IVES ZLLOW ZLUP CHSUPP: character: Type of support vessel = VESSEL: RIFLEX support vessel (Prescribed motions) = FLOATER: Floater force model IVES: integer: Support vessel number ZLLOW: real: Lower Z limit (local vessel system) \(\mathrm {[L]}\) ZLUP: real: Upper Z limit (local vessel system) \(\mathrm {[L]}\) One input line Specification of lines within present moonpool, one input line LINE-ID1 LINE-ID2 ....... LINE-IDi .........LINE-IDn LINE-ID: character(8): Line identifiers within moon pool The data groups Specification of support vessel moonpool and Specification of lines within present moonpool are to be repeated NLSPEC times. Rigid moonpool column may not be combined with CHMOT=NONE: No irregular motions, for irregular wave analysis . Rigid moonpool column may not be combined with IMOTD = 0: No motions, for regular wave analysis. If current is loaded in static analysis, the current forces will be removed at start of dynamic analysis for lines within moonpool and may create a transient. 6.4. Slug force calculations This data group is only given for INDINT=2 (see Non-linear force model). Note that slug forces can only be specified for single risers. 6.4.1. Data group identifier, one input line Restrictions The main riser line has to be modelled by beam elements Consistent formulation (Lumped mass option is prohibited) Assumptions The total slug mass is constant, \(\boldsymbol{\mathrm {M_S}}\). Initial length is \(\boldsymbol{\mathrm {L_{S0}}}\) The specified velocity refers to the gravity centre of the slug, initially at the half length. The slug specification is superimposed on the riser mass, including any internal fluid flow. The internal cross-section area is not used in the slug modelling The slug length is divided into sections. Initially the sections are of equal length \(\boldsymbol{\mathrm {dl_{S,0}}}\). The density, (mass per unit length) is constant within each section. Initially the mass per unit length is \(\boldsymbol{\mathrm {m_0=M_S/L_{S0}}}\) Input description for slug force specification SLUG FORCe SPECification 6.4.2. Specification of slug data, one input line TSLUG ICOSLG SLGLEN SLGMAS SLGVEL IDENS IVEL NCYCLE CYCTIM TSLUG: real, default: 0: Time when slug enters first end of main riser line \(\mathrm {[T]}\) ICOSLG: integer, default: 1: Interruption parameter =0: Analysis termination controlled by slug =1: Analysis termination controlled by specified length of simulation (TIME) SLGLEN: real: Initial slug length \(\mathrm {[L]}\) SLGMAS: real: Slug mass \(\mathrm {[M]}\) SLGVEL: real: Initial slug velocity \(\mathrm {[L/T]}\) IDENS: integer, default: 0: Control parameter density = 0: Constant density = 1: Variable density with vertical position IVEL: integer, default: 0: Control parameter velocity = 0: Constant velocity = 1: Variable velocity The specified velocity refers to the gravity centre of the slug NCYCLE: integer, default: 1: Number of slug cycles CYCTIM: real: Slug cycle time (dummy if NCYCLE = 1) \(\mathrm {[T]}\) if IDENS = 1: Z2 SLGMA2 ZREF Z2: real: Second vertical position where the slug unit mass is specified \(\mathrm {[L]}\) SLGMA2: real: Slug unit mass at Z2 \(\mathrm {[M/L]}\) ZREF: real < 0: Reference depth \(\mathrm {[L]}\) ZREF < \(\mathrm {Z_{MIN}}\), where \(\mathrm {Z_{MIN}}\) is lowest vertical position along the main riser line The unit mass at a specific z-position is calculated according to the following equation: \(\mathrm {m(Z_i)=A(Z_i-Z_{REF})^\alpha }\) where \(\mathrm {\alpha =\frac{ln(m_1/m_2)}{ln(\frac{Z_1-Z_{REF}}{Z_2-Z_{REF}})}}\) \(\mathrm {A=\frac{m_1}{(Z_1-Z_{REF})^\alpha }}\) \(\mathrm {m_1}\): SLGMAS/SLGLEN \(\mathrm {m_2}\): SLGMA2 \(\mathrm {Z_1}\): Vertical coordinate at inlet, end 1 of main riser line Figure 4. Internal slug flow if IVEL = 1: DELVEL VEXP DELVEL: real: Velocity specification VEXP: real: Exponent for velocity The unit mass at a specific z-position is calculated according to the following equation: \(\quad \mathrm {V(Z_i)=V_1-\Delta V|Z_i-Z_1|^\alpha}\) for \(\quad \mathrm {(Z_i-Z_1)>=0}\) \(\quad \mathrm {V(Z_i)=V_1+\Delta V|Z_i-Z_1|^\alpha}\) for \(\quad \mathrm {(Z_i-Z_1)<0}\) Where: \(\mathrm {V_1}\): Initial slug velocity (Velocity at inlet) \(\mathrm {\Delta V}\): DELVEL \(\mathrm {Z_i}\): Vertical coordinate at inlet, end 1 of main riser line \(\mathrm {\alpha }\): VEXP 6.5. Import of internal flow data from file This data group is only given for INDINT=2 (see Non-linear force model) 6.5.1. Data group identifier, 1 input line IMPOrt FLOW DATA 6.5.2. Specification of input flow file, one input line IMRL CHOPAD CHFFLW IMRL: integer, default: 0: Main riser line number. IMRL must be 0 in the present program version. = 0: All lines CHOPAD: character(4), default: REPL: Fluid contents option = REPL: Specified flow replaces that given in the Main Riser Line definition = ADDI: Specified flow is in addition to that given in the Main Riser Line definition CHFFLW: character(70): Name of flow data file The flow input file is described in See Internal flow description. 6.6. Dynamic current variation Available for nonlinear dynamic analysis, but only when the current profile is specified explicitly on the INPMOD input file. This means that this data group cannot be given for coupled analysis or when the current is specified on a CURMOD input file. However, dynamic current conditions can alternatively be specified using CURMOD. Varying current velocity and direction are specified at the current levels defined in the preceding static analysis. The varying current is to be described in a separate file. For description of the file format, confer chapter Description of Additional Input Files: Dynamic Current Variation. 6.6.1. Data group identifier, one input line DYNAmic CURRent VARIation 6.6.2. File name CHFCUR CHFCUR: character(80): File name with current velocity and direction ASCII file containing current velocity and direction at specified time instants. The velocity and directions have to be given at all levels defined in the preceding static analysis. 6.7. Dynamic nodal forces This data group enables the user to specify additional dynamic nodal force components. The force components may either be described by simple functions or read from a separate input file. For file description, see chapter Description of Additional Input Files: Dynamic Nodal Forces.. 6.7.1. Data group identifier, one input line DYNAmic NODAl FORCes 6.7.2. Number of specified components specified by functions or by time series on file NDCOMP CINPUT CHFLOA NDCOMP: integer: Number of load components to be specified CINPUT: character(6), default: 'NOFILE': Type of force specification CINPUT = NOFILE: Forces described by simple expression CINPUT = FILE: Forces described by time series on file CHFLOA: character(80): File name for time series of force components. Dummy if CINPUT = NOFILE 6.7.3. Force component description LINE-ID ILSEG ILNOD ILDOF CHICOO IFORTY TIMEON TIMEOF P1 P2 P3 LINE-ID: character(8): Line identifier ILSEG: integer: Segment number within actual line ILNOD: integer: Local node/element number within segment ILDOF: integer: Degree of freedom within the specified node/element ILDOF = 7…12 at end 2 of an element CHICOO: character(6): Coordinate system code CHICOO = GLOBAL: Force component refers to global system, unless the node has skew or vessel boundaries. If the node has skew or vessel boundaries, CHICOO=GLOBAL means that the load component acts in the skew (vessel) system. The force is applied at the specified node. CHICOO = LOCAL: Force component refers to local system. The force is applied to the specified element. IFORTY: integer: Force component type IFORTY = 1: Constant force IFORTY = 2: Harmonic force IFORTY = 3: Ramp TIMEON: real: Time for switching component on TIMOFF: real: Time for switching component off P1: real, default: 0: Force component parameter IFORTY = 1: Magnitude, \(\mathrm {[F,FL]}\) IFORTY = 2: Amplitude, \(\mathrm {[F,FL]}\) IFORTY = 3: Force derivative, \(\mathrm {[F/T,FL/T]}\) P2: real, default: 0: Force component parameter IFORTY = 1: Dummy IFORTY = 2: Period \(\mathrm {[T]}\) IFORTY = 3: Dummy P3: real, default: 0: Force component parameter IFORTY = 1: Dummy IFORTY = 2: Phase \(\mathrm {[deg]}\) IFORTY = 3: Dummy IFORTY, TIMEON, TIMEOFF, P1, P2 and P3 are dummy for CINPUT = FILE, time series on file. For file description, see chapter Description of Additional Input Files: Dynamic Nodal Forces.. For simulation time, t, TIMEON ⇐ t ⇐ TIMOFF the force component \(\mathrm {(F)}\) will be applied as: IFORTY = 1: \(\mathrm {F=P1}\) IFORTY = 2: \(\mathrm {F=P1\times sin(\frac{2\pi }{P2}\times (t-TIMEON)+P3\frac{\pi }{180})}\) IFORTY = 3: \(\mathrm {F=P1\times (t-TIMEON)}\) 6.8. Dynamic tension variation 6.8.1. Data group identifier, one input line DYNAmic TENSion VARIation 6.8.2. Specification of dynamic tension variation SNOD-ID TCX TCV TCA IOPDTV SNOD-ID: character(8): Supernode identifier for dynamic tension variation. Must be identical to the last node-id in stroke storage specification if stroke storage is specified. TCX: real, default: 0: Coefficient for tension variation due to relative displacement between vessel and riser \(\mathrm {[F/L]}\) TCV: real, default: 0: Coefficient for tension variation due to relative velocity between vessel and riser \(\mathrm {[FT/L]}\) TCA: real, default: 0: Coefficient for tension variation due to relative acceleration between vessel and riser \(\mathrm {[FT^2/L]}\) IOPDTV: integer, default: 0: Option for updating tension during iterations (relevant for nonlinear time domain analysis only): = 0: Not updated = 1: Updated The resulting dynamic tension is given by: \(\mathrm {\Delta T=TCX\times x+TCV\times \dot {x}+TCA\times \ddot {x}}\) where \(\mathrm {x}\) is the relative vertical displacement between the vessel and the riser. The vertical riser displacements are directly available in a nonlinear time domain analysis. In a linear analysis, the vertical displacements are estimated from the displacements along lines ILIN1 …. ILINN (as in linear stroke calculations). File storage for stroke response must be given if specification of dynamic tension variation is included. In both linear and nonlinear analyses platform motions will be modified for platform setdown if SETLEN > 0 in File storage for stroke response. 6.9. Time domain loading 6.9.1. Data group identifier, one input line TIME DOMain LOADing 6.9.2. Load type to be activated, one input line LOTYPE NLSPEC CINPUT CHFLOA IFORM LOTYPE: character: = SEGV: Segment length variation (Nonlinear analysis only) = TEMP: Temperature variation (Nonlinear analysis only) = PRES: Pressure variation (Nonlinear analysis only) = BOUN: Boundary change (Nonlinear analysis only) = VIVA: Harmonic loads from VIVANA (Nonlinear analysis only) = WINC: Winch run (Nonlinear analysis only) = WIND: Wind event. Only available for IWITYP=14, Stationary uniform wind with shear. = SHUT: Wind turbine shutdown fault options (Nonlinear analysis only) = BLAD: Wind turbine blade pitch fault options (Nonlinear analysis only) NLSPEC: integer, default: See below: Number of load specification to follow CINPUT: character, default: NOFILE: = NOFILE: All load specification given below = FILE: Load specification read from file CHFLOA CHFLOA: character, default: See below: Load specification file. Dummy for CINPUT = NOFILE IFORM: integer, default: 1: File format For LOTYPE = VIVA: NLSPEC = 1, CINPUT=FILE and IFORM=1 The default value of CHFLOA is <prefix>_ifnviv.ffi For LOTYPE = WIND: NLSPEC = 1, CINPUT=NOFILE For LOTYPE = SHUT: NLSPEC = 1, CINPUT=NOFILE For LOTYPE = BLAD: NLSPEC = 1, CINPUT=NOFILE 6.9.3. Segment length variation, NLSPEC input lines for LOTYPE = SEGV LINE-ID ISEG TBEG TENO SLRATE LINE-ID: character(8): Line identifier ISEG: integer: Local segment within line LINE-ID TBEG: real: Start time for segment length variation \(\mathrm {[T]}\) TEND: real: End time for segment length variation \(\mathrm {[T]}\) TEND > TBEG SLRATE: real: Segment length variation per time unit \(\mathrm {[L/T]}\) 6.9.4. Temperature variation, NLSPEC input lines if LOTYPE = TEMP LINE-ID ISEG IEL TBEG TEND TEMP LINE-ID: character(8): Line identifier ISEG: integer/character: Local segment number within line LINE-ID = 0 / ALL: All segments in specified line IEL: integer/character: Local element number within segment ISEG = 0 / ALL: All elements in specified segment TBEG: real: Start time for temperature variation \(\mathrm {[T]}\) TEND: real: End time for temperature variation \(\mathrm {[T]}\) TEND > TBEG TEMP: real: Temperature at end of temperature variation The temperature is varied linearly during the load group from the starting temperature ending with the temperature specified here. A linear variation of temperature over a sequence of elements may be specified by giving a negative element number at the second end of the linear variation. 6.9.5. Pressure variation, NLSPEC input lines if LOTYPE = PRES MRL-ID TBEG TEND PRESSI DPRESS VVELI MRL-ID: character(8): Reference to Main Riser Line identifier TBEG: real: Start time for pressure variation \(\mathrm {[T]}\) TEND: real: End time for pressure variation \(\mathrm {[T]}\) TEND > TBEG PRESSI: real, default: 0: Final pressure at inlet end \(\mathrm {[F/L^2]}\) DPRESS: real, default: 0: Final pressure drop \(\mathrm {[F/L^3]}\) VVELI: real, default: 0: Final fluid velocity \(\mathrm {[L^3/T]}\) Dummy in present version 6.9.6. Boundary change, 3 x NLSPEC input lines for LOTYPE = BOUN Time for boundary change TIMCHG TIMCHG: real: Time for boundary change \(\mathrm {[T]}\) Identification of node for boundary change IREF-ID ILSEG ILNODE IOP IREF-ID: character(8): Reference to line or supernode identifier. ILSEG: integer: If IREF-ID refers to a line, ILSEG is the segment number within this line If IREF-ID refers to a supernode, ILSEG must be zero ILNODE: integer: If IREF-ID refers to a line, ILNODE is the node number within segment ILSEG If IREF-ID refers to a supernode, ILNODE must be zero IOP: integer: Parameter for boundary change option = 0: Boundary conditions: fixed, pre-scribed or free = -1: Boundary conditions: rigid node connection (The node will become a slave node.) Ordinary (line end) supernodes and SIMO body nodes with CHLOCA_OPT='POSI' may have boundary change. Status for nodal degrees of freedom if IOP = 0 IPOS IX IY IZ IRX IRY IRZ IPOS: integer: Boundary condition type IPOS = 0: The node is fixed in global system IPOS = N: The node is attached to support vessel no N IX: integer: Boundary condition code for translation in X-direction IX = 0: Free IX = 1: Fixed of prescribed IY: integer: Boundary condition code for translation in Y-direction Same interpretation as for IX. IZ: integer: Boundary condition code for translation in Z-direction Same interpretation as for IX. IRX: integer: Boundary condition code for rotation around X-direction Same interpretation as for IX. IRY: integer: Boundary condition code for rotation around Y-direction Same interpretation as for IX. IRZ: integer: Boundary condition code for rotation around Z-direction Same interpretation as for IX. Identification of master node if IOP = 1 LINE-ID ILSEG ILNODE LINE-ID: character(8): Line identifier ILSEG: integer: Segment number within the actual line ILNODE: integer: Local node number within segment 6.9.7. Specification of harmonic loads from VIVANA, one input line for LOTYPE = VIVA CHFRQ ALIM ISEED TPLOT CHFRQ: character, default: DOMI: = ALL: All responses frequencies from VIVANA included = AMIN: Response frequencies with normalized cross-flow response larger than AMIN included = DOMI: Only the dominating response frequency included ALIM: real, default: 0: Cross-flow displacement to diameter ratio \(\mathrm {[1]}\) Dummy for CHFRQ \(\mathrm {\neq }\) ALIM ISEED: integer, default: 280495: Seed TPLOT: real, default: 2: VIV response plot interval. Key VIV results from the last TPLOT interval of the simulation are stored on the _dynmod.mpf file TPLOT > 0: Given as number of whole response periods TPLOT < 0: Given as time \(\mathrm {[T]}\) 6.9.8. Winch run, NLSPEC input lines for LOTYPE = WINC IWINCH TBEG TEND WIVEL IWINCH: integer: Winch number TBEG: real: Start time for winch run \(\mathrm {[T]}\) TEND: real: End time for winch run \(\mathrm {[T]}\) WIVEL: real: Winch velocity \(\mathrm {[L/T]}\) WIVEL > 0: Winching out, i.e. the winch run will increase the active line length. 6.9.9. Wind event specification, two or three input lines for LOTYPE = WIND In the following IEC 2005 refers to the standard IEC 61400-1 Wind turbines - Part 1: Design requirements - 2005. An IEC 2005 extreme wind event may only be applied to a stationary uniform wind with shear, IWITYP=14. Note that this input option is only available if one and only one wind turbine is specified in the system. Start time and wind turbine reference TIME WIND-TURBINE-ID TIME: real: Start time for wind event \(\mathrm {[T]}\) WIND-TURBINE-ID: character(8): Wind turbine identifier given in INPMOD. NONE may be given to skip the wind turbine reference for the events ECD, EOG and EDC with CLASS = NONE; i.e. detailed specification of event. Extreme wind event CHEVEN CLASS CHDIR CHEVEN: character(12): Extreme wind event. The following values are currently available: = IEC2005_ECD: IEC 2005 extreme coherent gust with direction change = IEC2005_EWSV: IEC 2005 extreme vertical wind shear = IEC2005_EWSH: IEC 2005 extreme horizontal wind shear = IEC2005_EOG: IEC 2005 extreme operating gust = IEC2005_EDC: IEC 2005 extreme direction change CLASS: character(4): Wind turbine class, ref IEC 2005. Legal values are IA, IIA, IIIA, IB, IIB, IIIB, IC, IIC, IIIC, S or NONE, detailed specification of event parameters. CHDIR: character(4): Direction of event. Dummy for CHEVEN = IEC2005_EOG. = POS: For ECD and EDC, the wind shifts clockwise (viewed from above). For EWSV, the wind increases at the top of the rotor disk and decrease at the bottom. For EWSH, the wind increases on the left side of the rotor disk and decrease on the right side when viewed along the shaft from the hub. = NEG: For ECD and EDC, the wind shifts counter-clockwise (viewed from above). For EWSV, the wind decreases at the top of the rotor disk and increases at the bottom. For EWSH, the wind decreases on the left side of the rotor disk and increases on the right side when viewed along the shaft from the hub. = NONE: Only allowed for CHEVEN = IEC2005_EOG. Additional input for wind turbine class S If CLASS = S, the following additional input line is given: VREF IREF VREF: real: Reference wind speed average over 10 min \(\mathrm {[L/T]}\) IREF: real: Expected value of the turbulence intensity at 15 m/s \(\mathrm {[1]}\) Detailed specification of IEC2005 ECD event If CLASS = NONE and CHEVEN = IEC2005_ECD, the following additional input line is given: VEL_EVENT DIR_EVENT TIME_EVENT VEL_EVENT: real, default: 0.0: Velocity change \(\mathrm {[L/T]}\) DIR_EVENT: real, default: 0.0: Direction change \(\mathrm {[deg]}\) TIME_EVENT: real > 0: Duration of event \(\mathrm {[T]}\) Detailed specification of IEC2005 EWSV or EWSH event If CLASS = NONE and CHEVEN = IEC2005_EWSV or IEC2005_EWSH, the following additional input line is given: VEL_EVENT TIME_EVENT VEL_EVENT: real, default: 0.0: Maximum velocity change at edge of rotor \(\mathrm {[L/T]}\) TIME_EVENT: real > 0: Duration of event \(\mathrm {[T]}\) Detailed specification of IEC2005 EOG event If CLASS = NONE and CHEVEN = IEC2005_EOG, the following additional input line is given: VEL_EVENT TIME_EVENT VEL_EVENT: real, default: 0.0: Range of velocity from minimum to maximum during the event \(\mathrm {[L/T]}\) TIME_EVENT: real > 0: Duration of event \(\mathrm {[T]}\) Detailed specification of IEC2005 EDC event If CLASS = NONE and CHEVEN = IEC2005_EDC, the following additional input line is given: DIR_EVENT TIME_EVENT DIR_EVENT: real, default: 0.0: Direction change \(\mathrm {[deg]}\) TIME_EVENT: real > 0: Duration of event \(\mathrm {[T]}\) 6.9.10. Wind turbine shutdown fault options The specifications given for turbine shutdown will overrule commanded blade pitch and torque, given by the wind turbine control system. Wind turbine blade pitch faults will override the wind turbine shutdown options. Note that this input option is only available if one and only one wind turbine is specified in the system. Start time and wind turbine reference TSTART WIND-TURBINE-ID TSTART: real: Start time for shutdown \(\mathrm {[T]}\) WIND-TURBINE-ID: character(8): Reference to wind turbine identifier Number of pairs in rate of change in pitch and maximum pitch NPAIR NPAIR: integer: Number of pairs in tabulated rate of pitch change and maximum pitch at the rate of pitch change Rate of change in pitch and maximum pitch at the rate of change in pitch, NPAIR input lines RATE MAX_PITCH RATE: real: Rate of change in pitch angle (absolute value) \(\mathrm {[deg/T]}\) RATE > 0 MAX_PITCH: real: Maximum pitch angle for the rate of change in pitch \(\mathrm {[deg]}\) MAXPITCH > 0 MAX_PITCH values must be given in increasing order. Example: Type of shutdown Pitch change rate Maximum pitch normal 1.0 deg/T to 90.0 deg Example: Type of shutdown Pitch change rate Maximum pitch open-loop 8.0 deg/T to 40.0 deg - 4.0 deg/T to 90.0 deg Example: Type of shutdown Pitch change rate Maximum pitch emergency 8.0 deg/T to 90.0 deg Generator torque fault options CHFAULT CHFAULT: character(6): = NONE: No generator torque fault, the calculated generator torque will be applied in full = LOSS: Total loss of generator torque = BACKUP: Backup power, generator torque will follow scaled torque control Scale factor for generator torque, One input line for CHFAULT = BACKUP SF SF: real: Scale factor for generator torque SF >= 0 Mechanical brake option CHBRAKE CHBRAKE: character(6): = NONE: No mechanical brake = BRAKE: Mechanical brake (Linear damping) Torque damping coefficient and brake uploading duration, One input line for CHBRAKE = BRAKE TORQUE_DAMP UPL_DURATION TORQUE_DAMP: real: Linear torque damping coefficient \(\mathrm {[FLT/deg]}\) TORQUE_DAMP >= 0 UPL_DURATION: real: Brake uploading duration to full braking torque \(\mathrm {[T]}\) UPL_DURATION >= 0 6.9.11. Wind turbine blade pitch fault options Wind turbine blade pitch faults will override commanded blade pitch given by the wind turbine control system or by the wind turbine shutdown options. Note that this input option is only available if one and only one wind turbine is specified in the system. Wind turbine reference WIND-TURBINE-ID WIND-TURBINE-ID: character(8): Reference to wind turbine identifier Number of blades for fault specification NBL_FAULT NBL_FAULT: integer: Number of blades for fault specification NBL_FAULT >= 0 The subsequent input specification must be given per blade with pitch fault Start time and line (foil blade) reference for fault specification TSTART LINE-ID TSTART: real: Start time for blade pitch fault \(\mathrm {[T]}\) LINE-ID: character(8): Reference to line identifier Type of blade pitch fault CHFAULT CHFAULT: character(4): = SEIZ: Seized - Fixed pitch from time of occurrence = RUNA: Runaway - Pitch change rate from time of occurrence to final pitch = BIAS: Actuator bias - Fixed pitch fault from time of occurrence Rate of change in pitch and final pitch, One input line for CHFAULT = RUNA RATE FINAL_PITCH RATE: real: Rate of change in pitch (absolute value) \(\mathrm {[deg/T]}\) RATE >= 0 FINAL_PITCH: real: Final pitch \(\mathrm {[deg]}\) Pitch deviation from required pitch, One input line for CHFAULT = BIAS DEL_PITCH UPL_DURATION DEL_PITCH: real: Fixed pitch deviation from required pitch \(\mathrm {[deg]}\) UPL_DURATION: real: Bias uploading duration to full pitch deviation \(\mathrm {[T]}\) UPL_DURATION >= 0 6.10. File storage of displacement response Before specifying file storage of response, note that meaningful output from OUTMOD can be dependent on which and how much information that is stored on file from DYNMOD. Examples of such output options in OUTMOD are time series of element angles and distance between elements, see Element angle time series from time domain analysis and Distance time series calculated from the time domain analyses. There are limitations in storage capacity due to: Disk/user size 6.10.1. Data group identifier, one input line DISPlacement RESPonse STORage 6.10.2. Specification of displacements to be stored Amount of storage, one input line IDISP NODISP IDISFM IDISP: integer: Code for storage of nodal displacements. Storage for every IDISP time step (IDISP=2 gives storage for every second step). NODISP: integer > 0: Number of input lines given specifying node numbers where displacements are stored. IDISFM: integer, default: 0: integer: Format code for storage and/or output of nodal displacements. IDISFM = 0: Storage only on ifndyn file. IDISFM = 1: Storage on ifndyn file and additional file in ASCII format. IDISFM = 2: Storage on ifndyn file and additional file in BINARY format. IDISFM = -1: Storage only on additional file in ASCII format. Results are not available in OUTMOD. IDISFM = -2: Storage only on additional file in BINARY format. Results are not available in OUTMOD. Note that data must be stored on the ifndyn file in order to be available for OUTMOD. If IDISFM\(\mathrm {\neq }\) 0 is specified, an additional result file and a key file will be created. The file names will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_noddis.asc and an additional binary file will be <prefix>_noddis.bin. The key file key_<prefix>_noddis.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. Specification of nodes for displacement storage, NODISP input lines LINE-ID ISEG INOD LINE-ID: character(8): Line identifier ISEG: integer: Segment number of line INOD: integer/character: Local node number on actual segment Consecutively numbered nodes may be specified implicitly by assigning a negative value to the last of two adjacent INOD. In this case LINE-ID and ISEG must be the same for the two nodes. All nodes within one segment may be specified by simply giving ALL as input to INOD. 6.11. File storage for internal forces 6.11.1. Data group identifier, one input line FORCe RESPonse STORage 6.11.2. Specification of forces to be stored Amount of storage, one input line IFOR NOFORC IFORFM IELTFM IBOTFM IFOR: integer: Code for file storage of internal forces. Forces are stored for every IFOR time step. (IFOR=3 gives storage for every third step) NOFORC: integer > 0: Number of input lines given to specify elements for which forces are stored. IFORFM: integer, default: 0: Format code for storage and / or output of element forces IFORFM = 0: Storage only on ifndyn file IFORFM = 1: Storage on ifndyn file and additional file in ASCII format IFORFM = 2: Storage on ifndyn file and additional file in BINARY format IFORFM = -1: Storage only on additional file in ASCII format. Results are not available in OUTMOD. IFORFM = -2: Storage only on additional file in BINARY format. Results are not available in OUTMOD. IELTFM: integer, default: 0: Format code for output of element transformation matrices IELTFM = 0: No output IELTFM = ±1: Output on additional file in ASCII format IELTFM = ±2: Output on additional file in BINARY format IBOTFM: integer, default: 0: Format code for output of seafloor / soil contact results. Nonlinear analysis only. IBOTFM = 0: No output IBOTFM = ±1: Output on additional file in ASCII format IBOTFM = ±2: Output on additional file in BINARY format Note that data must be stored on the ifndyn file in order to be available for OUTMOD. If IFORFM\(\mathrm {\neq }\) 0 is specified, an additional result file and a key file will be created. The file names will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_elmfor.asc and an additional binary file will be <prefix>_elmfor.bin. The key file key_<prefix>_elmfor.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. For nonlinear analysis with pipe-in-pipe elements, the contact forces will be written to <prefix>_cntfor.asc or .bin if IFORFM\(\mathrm {\neq }\) 0. The contents are described on the corresponding key file key_<prefix>_cntfor.txt. Roller contact forces will be stored on separate result files if IDCOM = LAYFLX, see INPMOD: Selection of riser type and identifier. If IELTFM\(\mathrm {\neq }\) 0 is specified, element transformation matrices will be written to an additional result file for elements for which force storage is specified. The file name will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_elmtra.asc and an additional binary file will be <prefix>_elmtra.bin. The key file key_<prefix>_elmtra.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. If IBOTFM\(\mathrm {\neq }\) 0 is specified, results for seafloor contact elements and / or soil layer profile contact elements will be written to an additional file for contact elements that are attached to beam or bar elements for which force storage is specified. The file name will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_botres.asc and an additional binary file will be <prefix>_botres.bin. The key file key_<prefix>_botres.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. Specification of elements for force storage, NOFORC input lines LINE-ID ISEG IEL LINE-ID: character(8): Line identifier ISEG: integer: Local segment number within line LINE-ID IEL: integer/character: Local element number within segment ISEG = ALL: All elements in specified segment Consecutively numbered elements may be specified implicitly by assigning a negative value to the last of two adjacent elements, IEL. In this case LINE-ID and ISEG must be the same for the two elements. All elements within one segment may be specified by simply giving ALL as input to IEL. 6.12. File storage for curvature response Curvature estimates based on nodal displacements may be generated by OUTMOD (see Curvature time series calculated from dynamic nodal displacements) even though curvatures are not stored from DYNMOD. 6.12.1. Data group identifier, one input line CURVature RESPonse STORage 6.12.2. Specification of curvature to be stored Amount of storage, one input line ICURV NOCURV ICURFM ICURV: integer: Code for storage of curvature response. Curvature is stored for every ICURV time step NOCURV: integer > 0: Number of input lines given to specify elements for which curvatures are stored. ICURFM: integer, default: 0: integer: Format code for storage and/or output of element curvature. ICURFM = 0: Storage only on ifndyn file. ICURFM = 1: Storage on ifndyn file and additional file in ASCII format. ICURFM = 2: Storage on ifndyn file and additional file in BINARY format. ICURFM = -1: Storage only on additional file in ASCII format. Results are not available in OUTMOD. ICURFM = -2: Storage only on additional file in BINARY format. Results are not available in OUTMOD. Note that data must be stored on the ifndyn file in order to be available for OUTMOD. If ICURFM\(\mathrm {\neq }\) 0 is specified, an additional result file and a key file will be created. The file names will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_elmcur.asc and an additional binary file will be <prefix>_elmcur.bin. The key file key_<prefix>_elmcur.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. Specification of elements for curvature storage, NOCURV input lines LINE-ID ISEG IEL LINE-ID: character(8): Line identifier ISEG: integer: Local segment number within line LINE-ID IEL: integer/character: Local element number within segment ISEG = ALL: All elements in specified segment Consecutively numbered elements may be specified implicitly by assigning a negative value to the last of two adjacent elements, IEL. In this case LINE-ID and ISEG must be the same for the two elements. All elements within one segment may be specified by simply giving ALL as input to IEL. 6.13. File storage for hydrodynamic loads 6.13.1. Data group identifier, one input line HYDRodynamic LOAD STORage 6.13.2. Specification of forces to be stored Amount of storage, one input line IHLO NOHLO IHLOFM IHLO: integer: Code for file storage of hydrodynamic loads. Forces are stored for every IHLO time step. (IHLO=4 gives storage for every fourth simulation step) NOHLO: integer > 0: Number of input lines given to specify elements for which hydrodynamic loads are stored. IHLOFM: integer, default: 0: Format code for storage of hydrodynamic loads IFORFM = 1: Storage on the ASCII file <prefix>_hydloa.asc IFORFM = 2: Storage on the BINARY file <prefix>_hydloa.bin The key file key_<prefix>_hydloa.txt will describe how data is stored on the file. The key file may be viewed in a text editor. Specification of elements for hydrodynamic load storage, NOFHLO input lines LINE-ID ISEG IEL ILEVHLO LINE-ID: character(8): Line identifier ISEG: integer: Local segment number within line LINE-ID = 0: All segments in the specified line IEL: integer: Local element number within segment ISEG = 0: All elements in the specified segment ILEVHLO: integer, 0<ilevhlo<4, default: 1: Level of output. = 1: Minimum: Total hydrodynamic load excepting added mass contribution = 2: Medium: Available for elements with time domain VIV loading only. Total hydrodynamic load excepting added mass contribution, average relative velocity, average cross-flow, in-line and higher harmonic load amplitude = 3: Maximum: Available for elements with time domain VIV loading only. Total hydrodynamic load excepting added mass contribution, relative velocity at both ends, Morison, cross-flow, in-line and higher order loads at both ends. 6.14. Envelope curve specification This data group enables the user to compute envelopes from both regular and irregular analysis. For irregular analysis mean and standard deviation of response will be printed on the _dynmod.res file. 6.14.1. Data group identifier, one line ENVElope CURVe SPECification 6.14.2. Specification Options for calculation and printing IENVD IENVF IENVC TENVS TENVE NPREND NPRENF NPRENC IFILMP IENVD: integer, default: 1: Calculation option for displacement envelopes = 0: not calculated = 1: calculated IENVF: integer, default: 1: Calculation option for force envelopes = 0: not calculated = 1: calculated IENVC: integer, default: 1: Calculation option for curvature envelopes = 0: not calculated = 1: calculated TENVS: real: Simulation start time for calculating envelopes \(\mathrm {[T]}\) TENVE: real, default: \(\mathrm {10^{6}}\): Simulation end time for calculating envelopes \(\mathrm {[T]}\) NPREND: integer, default: 0: Print option for displacement envelopes = 0: Not printed = 1: print NPRENF: integer, default: 0: Print option for force envelopes = 0: not printed = 1: print NPRENC: integer, default: 0: Print option for curvature envelopes = 0: not printed = 1: print IFILMP: integer, default: 2: MatrixPlot file option; specifies amount of results written to the file <prefix>_dynmod.mpf. 0 ⇐ IFILMP ⇐ 4. = 0: No print = 1: Minimum values, maximum values and standard deviations = 2: Minimum values, maximum values and standard deviations (identical to specifying IFILMP = 1) = 3: Minimum values, maximum values, standard deviations, mean values and mean-crossing periods = 4: Minimum values, maximum values, standard deviations, mean values, mean-crossing periods, skewness and kurtosis Note that the mean-crossing period, skewness and kurtosis will be inaccurate for time series with constant or near constant values. 6.15. File storage for stroke response The stroke is stored for presentation and / or post-processing in OUTMOD 6.15.1. Data group identifier, one input line STROke RESPonse STORage 6.15.2. Specification of stroke calculation and storage ISTRO SNOD-ID IOPSTR SETLEN XRSTRO YRSTRO NLINST LINE-ID1 .. LINE-IDnlinst ISTRO: integer, default: 1: Code for storage of stroke response. Storage for every ISTRO time step (ISTRO=2 gives storage for every second step) SNOD-ID: character(8): Supernode identifier for stroke calculation IOPSTR: integer, default: 0: Option for reference coordinates = 0: Initial stressfree configuration used as reference = 1: Final static configuration used as reference (under implementation) SETLEN: real, default: 0: Tendon length for set-down correction XRSTRO: real, default: 0: Global X coordinate of node INODST’s reference point for set-down calculations. Dummy of SETLEN = 0. YRSTRO: real, default: 0: Global Y coordinate of node INODST’s reference point for set-down calculations. Dummy of SETLEN = 0. NLINST: integer, default: 0: Number of lines used in calculating stroke Dummy for nonlinear analysis Lines (line identifiers) used in stroke calculation Dummy for nonlinear analysis LINE-ID1: character(8): . . . LINE-IDnlinst: character(8): Stroke may only be calculated for supernodes. No set-down correction if SETLEN = 0.0 6.16. File storage for sum forces The element sum forces are the sum of the stiffness, damping and inertia forces. The sum force in the local axial direction will be stored for each specified element. 6.16.1. Data group identifier, one input line SUMFORCe RESPonse STORage 6.16.2. Specification of forces to be stored Amount of storage, one input line ISFOR NOSFOR ISFOFM ISFOR: integer: Code for file storage of sum forces. Forces are stored for every ISFOR time step (ISFOR=3 gives storage for every third step) NOSFOR: integer > 0: Number of input lines given to specify elements for which sum forces are stored. ISFORM: integer, default: -1: integer: Format code for storage and/or output of sum element forces. ISFORM = -1: Storage on additional file in ASCII format only. ISFORM = -2: Storage on additional file in BINARY format only. This data group is available for nonlinear time domain analysis only. If ISFORM\(\mathrm {\neq }\) 0 is specified, an additional result file and a key file will be created. The file names will be based on the name of the DYNMOD result file; <prefix>_dynmod.res. An additional ASCII file will be <prefix>_elmsfo.asc and an additional binary file will be <prefix>_elmsfo.bin. The key file key_<prefix>_elmsfo.txt will describe how data is stored on the additional output file. The key file may be viewed in a text editor. Note that axial force presented by other data groups is the element effective tension, where only internal forces from the stiffness are included. The damping and inertia forces in the other elements are included inherently through nodal displacements. It is only the internal element mass and damping forces in the element that are not included. The element sum forces presented by this data group also include damping and inertia forces for the element. The element sum forces can be viewed as an equivalent to reaction forces at the end of the element. Specification of elements for force storage, NOSFOR input lines LINE-ID ISEG IEL LINE-ID: character(8): Line identifier ISEG: integer: Local segment number within line LINE-ID IEL: integer/character: Local element number within segment ISEG = ALL: All elements in specified segment Consecutively numbered elements may be specified implicitly by assigning a negative value to the last of two adjacent elements, IEL. In this case LINE-ID and ISEG must be the same for the two elements. All elements within one segment may be specified by simply giving ALL as input to IEL. 6.17. File storage of support forces This option enables export of support forces to a binary file. 6.17.1. Data group identifier, one input line SUPPort FORCe STORage Amount of storage, one input line DT_SFOR NS ISFOR DT_SFOR: real, default: 0: Desired time interval for storage [T] = 0: Storage at each simulation time step NS: integer > 0: integer: Number of input lines given to specify the SIMO bodies and support vessel for storage of support forces. ISFOR: integer, default: 2: integer: File format code for storage = 1: ASCII format = 2: Storage on file in binary format. Note that DT_SFOR will be adjusted to get an integer ratio between the simulation time step DT and the specified storage interval DT_SFOR. Support force identification for storage, NS input lines SFOR CHCOR SFOR : character(8) or integer: SIMO body or support vessel identifier CHCOR: character(8), default= BVLOC: Coordinate system for support forces = GLOB : Global coordinate system = BVLOC: SIMO body of support vessel coordinate system Note that that the support vessel is given as integer input. The SIMO body has an character ID as identifier. 6.18. File storage for wind turbine responses This option enables export of wind turnine key responses to file in binary or ASCII format 6.18.1. Data group identifier, one input line TURBine RESPonse STORage Time interval for storage, one input line DT_WTR DT_WTR: real: Desired time interval for storage [T] DT_WTR = 0: Storage at each simulation time step Note that DT_WTR will be adjusted to get an integer ratio between the simulation time step DT and the specified storage interval DT_WTR. Amount of storage, one input line NOTURB ITURBFM NOTURB: integer: Number of wind turbines for storage ITURBFM: integer: File format code for storage ITURBFM = 1: Storage on file in ASCII format. ITURBFM = 2: Storage on file in binary format. The wind turbine responses are written to <prefix>_witurb.asc or <prefix>_witurb.bin. The contents are described in key_<prefix>_witurb.txt Wind turbine identification for storage, NOTURB input lines TURB-ID TURB-ID: character(8): Wind turbine identifier 6.19. File storage for wind turbine blade responses This option enables export of wind turbine blade responses to file in binary or ASCII format. 6.19.1. Data group identifier, one input line WTBLade RESPonse STORage Specification of the amount of responses, one input line AMOUNT AMOUNT: character(3): Amount of blade responses storage AMOUNT = MIN: Minimum amount of responses: Drag and lift force intensities in foil system Relative wind velocity in foil system - Angle of attack in foil system AMOUNT = MED: Medium amount of responses. In addition to minimum amount: Drag-, lift and moment coefficients in foil system Induced wind speed in foil system Remote incoming wind speed including tower effect in foil system Separation point position in foil system Axial and tangential induction factors in rotor system Axial and tangential load intensities in rotor system Annulus average axial- and tangential induction velocity AMOUNT = MAX: Maximum amount of responses. In addition to medium amount: Transformation matrix between foil and rotor systems Time interval for storage, number of input lines and file format code, one input line DT_TBR NOSPEC IBLADFM DT_TBR: real: Desired time interval for storage [T] DT_TBR = 0: Storage at each simulation time step NOSPEC: integer > 0: Number of input lines given to specify elements for which blade responses are stored. IBLADFM: integer: File format code for storage IBLADFM = 1: Storage on file in ASCII format. IBLADFM = 2: Storage on file in binary format. Note that DT_TBR will be adjusted to get an integer ratio between the simulation time step DT and the specified storage interval DT_TBR. The wind turbine responses are written to <prefix>_blresp.asc or <prefix>_blresp.bin. < The contents are described in key_<prefix>_blresp.txt Specification of elements for blade response storage, NOSPEC input lines LINE-ID ISEG IEL LINE-ID: character(8): Line identifier ISEG: integer/character: Local segment number within line LINE-ID IEL: integer/character: Local element number within segment ISEG All elements within the line may be specified by simply giving ALL as input to ISEG. Thus IEL will be dummy input. All elements within one segment may be specified by giving ALL as input to IEL. 6.20. Export of element responses This option enables export of element responses for subsequent communication with general advanced animation tools. The instruction is applicable for non-linear dynamic analysis only. 6.20.1. Data group identifier, one input line STORe VISUalisation RESPonses 6.20.2. Amount of response storage and file format, one input line TCONDS TCONDE DELT CHFORM TCONDS: real, default: 0: Start time for export TCONDE: real, default: \(\mathrm {10^5}\): End time for export DELT: real, default: See below: Time increment for export CHFORM: character: = VIS: Export to file format used by the computer program SIMVIS for response visualization subsequent to dynamic analysis = RAF: Export to file format of type RAF Default values of DELT: DTWF: Time increment used for pre-sampling of irregular waves and prescribed motions DT: Time increment used in time integration for regular analysis 6.20.3. Detailed specification of exported element responses This data group is optionally given for CHFORM = VIS In present version it is possible to specify element responses in form of effective tension, resulting curvature and longitudinal stress (if available). By default all available element responses for all lines will be exported. This input line makes it possible limit or specify response types for selected lines in the system. Number of input lines: as many as necessary. OPTION CHRESP CHILIN OPTION: character: = STORE = NOSTORE CHRESP: character: Response type to be exported = EFF-AX-FORCE: Effective tension = RES-CURV: Resultant curvature = LONG-STRESS: Longitudinal stress = ALL: All of the above described responses CHILIN: character: = LINE-ID: Line identifier = ALL: All lines 6.21. Termination of input data To terminate an input data stream, simply give the following, which is interpreted as a data-group identifier. END 7. Description of Additional Input Files 7.1. Dynamic Current Variation The file CHFCUR specified in Dynamic current variation, contains the description of dynamic current variation. The file is a free format sequential ASCII-file. The current velocity and direction have to be specified at all levels defined in the preceding static analysis. The static current profile is interpreted as the current profile at time equal to zero. The dynamic current profile is described at an arbitrary number of time instants, given by increasing values. Linear interpolation is used for intermediate values. If the last defined time instant is exceeded during simulation, the current profile is assumed constant and equal to the last specification for the continued simulation. File description 7.1.1. Number of specified time instants, one input line NDYCUR NDYCUR: integer > 1: The number of time instants for which current profile is given. The input data in Number of levels and time instant, one input line and Current velocity and direction, one input line per current level, i.e. NLCUR input lines (below) must be given in one block for each defined time instant. Number of levels and time instant, one input line NLCUR TIMDCU NLCUR: integer: Number of levels in current profile. The number of levels has to be equal the number used in the preceding static analysis TIMDCU: real > 0: Time instant for the specified current profile \(\mathrm {[T]}\) Current velocity and direction, one input line per current level, i.e. NLCUR input lines CURDIR CURVEL CURVEZ CURDIR: real: Direction of current velocity. The angle is measured in degrees from global x-axis counter clockwise to the current vector, confer Current parameters CURVEL: real, default: 0: Current velocity \(\mathrm {[L/T]}\) CURVEZ: real, default: 0: Vertical current velocity \(\mathrm {[L/T]}\) 7.2. Dynamic Nodal Forces The file CHFLOA specified in Dynamic nodal forces, contains the description of dynamic nodal load components; i.e. user-deined external dynamic loads given as time series. The file is a free format sequential ASCII-file. Two alternative formats are available; the original format with multiple input lines for each time instant loads are specified for and the column format with one line for each time instant loads are specified for. The first input line in the file is used to determine which format the file is read in. If only one number is found on the first input line, the file is read using the original format. If more than one number is found, the file is read using the column format. The dynamic nodal load components are described by values at specified time instants, which must be increasing. Intermediate values are found by linear interpolation. Between the start of the simulation and the first time instant with specified loads, the loads are linearly increased from zero to the first values given. If the simulation continues after the last defined time instant, the nodal load components are kept constant at the last values given. The number of nodal load components, location and direction are defined in Dynamic nodal forces. This data group also defines the order in which the load components are to be specified on the file. 7.2.1. File description - original format 7.2.2. Number of specified time instants, one input line NTDFO NTDFO: integer >= 1: Number of time instants for which nodal load components are specified. The input data in Number of load components and time instant, one input line and Load components, MDCOMP input lines (below) must be given in one block for each defined time instant. 7.2.3. Number of load components and time instant, one input line MDCOMP TIMDFO MDCOMP: integer: Number of load components. Used for control: MDCOMP = NDCOMP NDCOMP is specified in Dynamic nodal forces TIMDFO: real > 0: Time instant for the specified load components \(\mathrm {[T]}\) 7.2.4. Load components, MDCOMP input lines RLMAG RLMAG: real: Magnitude of load component \(\mathrm {[F]}\), \(\mathrm {[FL]}\) 7.2.5. File description - column format 7.2.6. Time Step and Load Components, one line for each time step TIMDFO RLMAGi ..... RLMAGn TIMDFO: real > 0: Time instant for the specified load components \(\mathrm {[T]}\) RLMAGi: real: Magnitude of load component \(\mathrm {[F]}\), \(\mathrm {[FL]}\) RLMAGi must be repeated n=MDCOMP times. 7.3. Diffracted Wave Transfer Functions at Points The file CHFDIF specified in Irregular Waves contains the wave kinematics transfer functions. 7.3.1. Data group identifier, one input line FIRSt ORDEr DIFFracted wave transfer functions 7.3.2. Text describing the linear incoming wave to diffracted wave transfer functions, two input lines TXDI1 TXDI1: character(60): Character string 7.3.3. Point reference, one input line PTNOUS IVES PTNOUS: integer: Point number defined by user IVES: integer: Support vessel number 7.3.4. Point coordinates, one input line XBDY YBDY ZBDY XBDY: real: x-coordinate of where transfer function is calculated, given in support vessel coordinate system \(\mathrm {[L]}\) YBDY: real: y-coordinate of where transfer function is calculated, given in support vessel coordinate system \(\mathrm {[L]}\) ZBDY: real: z-coordinate of where transfer function is calculated, given in support vessel coordinate system \(\mathrm {[L]}\) 7.3.5. Dimensioning parameters, one input line NDIR NFRE ITYPIN NDIR: integer: Total number of wave directions (for this point) NFRE: integer: Total number of frequencies (for this point) ITYPIN: integer: Code for which format the transfer functions are given in = 1: Complex form = 2: Amplitude ratio \(\mathrm {[1]}\) and phase \(\mathrm {[deg]}\) = 3: Amplitude ratio \(\mathrm {[1]}\) and phase \(\mathrm {[rad]}\) 7.3.6. Data identification, one input line WAVE DIREctions DIFFracted wave transfer functions 7.3.7. Directions, NDIR input lines IDIR DIR IDIR: integer: Direction number (between 1 and NDIR) DIR: real: Propagation direction of incoming wave, \(\mathrm {[deg]}\) 7.3.8. Data identification, one input line WAVE FREQuencies DIFFracted wave transfer functions 7.3.9. Frequencies, NFRE input lines IFRE FRE IFRE: integer: Frequency number (between 1 and NFRE) FRE: real: Angular frequency of incoming wave, \(\mathrm {[rad/T]}\) 7.3.10. Data identification, one input line WAVE ELEVation DIFFracted wave transfer function or XVELocity DIFFracted WAVE transfer function YVELocity DIFFracted WAVE transfer function ZVELocity DIFFracted WAVE transfer function 7.3.11. Diffracted wave transfer function, NDIR x NFRE input lines IDIR IFRE A B IDIR: integer: Direction number IFRE: integer: Frequency number A: real: Interpretation according to value of ITYPIN ITYPIN = 1: Real part ITYPIN = 2: Amplitude ratio \(\mathrm {[1],[rad/m]}\) ITYPIN = 3: Amplitude ratio \(\mathrm {[1],[rad/m]}\) B: real: Interpretation according to value of ITYPIN ITYPIN = 1: Imaginary part ITYPIN = 2: Phase angle \(\mathrm {[deg]}\) ITYPIN = 3: Phase angle \(\mathrm {[rad]}\) Transfer functions for accelerations will be calculated based on velocity transfer functions 7.4. Internal flow description The file "CHFFLW" specified in Import of internal flow data from file contains a description of the time-varying internal flow. 7.4.1. Heading, one input line <TEXT>: character(78): The heading will be echoed on the <prefix>_dynmod.res result file. 7.4.2. Specification of internal flow conditions. Data groups Specification of time… and Specification of flow conditions… (below) are repeated as many times as necessary. At least two time steps must be given. Specification of time, one input line CHIDEN TIME CHIDEN: character(4): = TIME TIME: real: Time for the following specified flow conditions Specification of flow conditions, as many input lines as needed. (Zero input lines may be given.) IFE1 IFE2 DEN VEL IFE1: integer: First flow element with these conditions IFE2: integer: Last flow element with these conditions DEN: real: Density of contents \(\mathrm {[M/L^3]}\) VEL: real: Velocity of contents \(\mathrm {[L/T]}\) The elements in the MRL(s) are numbered consecutively along the MRL. A table of the flow element numbering may be found on the <prefix>_stamod.res file. 7.4.3. End, one input line END