New & Noteworthy

1. General information

  • Version no. 4.8.0

2. RIFLEX

2.1. Chain Cross Section

A new Chain Cross Section is added to RIFLEX.

Inputs are

  • Nominal diameter

  • Steel grade

  • Construction type:

    • Studless

    • Stud link

The input for this model element will generate an Axisymmetric cross-section representing the properties for a chain behind the scenes. If more details are needed it is possible to convert the cross section model to a regular Axisymmetric cross section.

Marine growth can be added and the NORSOK N-003 marine growth profile will be generated The marine load growth will automatically be added to the static loading.

sima480 chain cs
Figure 1. Chain Cross Section
sima480 crs convert axisym
Figure 2. Convert cross section to axisymmetric cross section
sima480 add marine growth
Figure 3. Add marine growth
sima480 add marine growth loadgroup
Figure 4. Add marine growth load group
sima480 norsok
Figure 5. NORSOK N-003 marine growth profile

2.2. Marine Growth input for NORSOK N-003

In the Marine Growth component it is now possible to import values defined in NORSOK N-003 standard for 59-72 degree North, see Marine Growth component editor.

sima480 import norsokN003
Figure 6. Apply NORSOK N-003 marine growth profile

2.3. Fibre Rope Wizard

To help the users create the fibre rope cross section we have created a new wizard.

The different options are

  • Default

    • This will create the default Fibre Rope cross section with no additional input. A fiber rope model is needed and must be created.

  • Different options for polyester rope:

    • Linear : An axis symmetric cross section with linear stiffness model based on rope diameter

    • Bilinear: An axis symmetric cross section with static-dynamic stiffness model based on rope diameter

    • Syrope : A fibre rope cross section based on ABS Syrop model

sima480 fibre rope cs
Figure 7. Fibre Rope Wizard

2.4. Fibre Rope Improvements

2.4.1. Max tension of Fibre rope segments

Key results are presented for all segments with Fibre rope cross-sections. The key-results are

  • maximum tension at the end of the static analysis

  • input maximum historical tension

sima480 fibre rope max tension
Figure 8. Fibre Rope Results

2.4.2. Fibre rope initial elongation

The initial elongation of Fibre rope segments is now applied gradually during a load group. If Initially pre-stressed segments is specified, the fibre rope elongation will be applied in this load group together with any stress-free segment lengths specified by the user. Otherwise, the elongation will be automatically applied in the first load group. This improves convergence during static analysis.

2.4.3. Fibre rope original curve

It is no longer necessary to specify the original curve for fibre rope cross sections. The original curve is not used in the analyses.

2.5. Storage of the touch down point (TDP) location

Storage of the touch down point (TDP) location is now available.

The following results are stored

  • seafloor/soil contact results for the TDP-region

  • the arc length from super node 1 on the line

  • the global coordinate x- and y of the TDP point

Storage of TDP results may be specified in the new Bottom Contact storage section of Dynamic Calculation Parameters in the UI or in the data group BOTTOM CONTACT STORAGE in the input file.

The results are written to the key-file and bin-file

  • key_<prefix>_botres.txt

  • <prefix>_botres.bin

For details, see Riflex/Input Reference/Input to DYNMOD/File storage for bottom contact

sima480 tdp inp
Figure 9. Specification of bottom contact storage
sima480 tdp arc
Figure 10. Result - arc length from super node 1 to TDP
sima480 tdp result
Figure 11. Result - indentation into seafloor

2.6. Added missing signals to Bladed style controller

AVRSwap record 14 (measured shaft power) and 23 (measured generator torque) are added to controller input.

In regards to the ROSCO controller, SIMA supports the following versions:

Version Note

2.6

Can now be used with EKF enabled (WE_Mode=2)

2.7

Can now be used with EKF enabled (WE_Mode=2)

2.9

Ext_Interface=0 must be set to be used in SIMA.

Note: ROSCO v2.8 does not work with SIMA as it requires the use of awrSwap records not defined by the Bladed standard. The Ext_Interface=0 switch in v2.9 will force the controller to use the standard ones.

2.7. User defined skew wake parameter

An optional user defined factor, K, for scaling the magnitude of the existing skewed wake correction in the BEM formulation for wind turbines can be specified.

The skew wake parameter is set by choosing Advanced aerodynamic options in the wind turbine specifications. In the Advanced aerodynamic options, select and specify the skew wave factor.

sima480 skew aeroinpt
Figure 12. Advanced aerodynamic options
sima480 skew wake
Figure 13. Skew wake parameter

2.8. Wind files from TurbSim (OpenFAST version 3.2.0 and later)

Wind fields generated with TurbSim, integrated with OpenFAST version 3.2.0 and later, can now be used in simulations.

The clockwise parameter was removed in TurbSim (OpenFAST version 3.2.0). If this parameter is not found in the .sum-file it is now assumed that the parameter is False, i.e. the file follows the left hand convention which is the case for files generated by TurbSim 3.2.0 and later.

Download TurbSim

  • The latest version (and ongoing development) can be found on GitHub in the OpenFast repository.

  • Legacy TurbSim version 2.0 can be downloaded at the NREL web-site.

2.8.1. Generator Efficiency

A generator efficiency for conversion of mechanical to electrical power can be defined by the user. If a generator efficiency is specified in the controller configuration file, that same value should also be specified here.

The Generator Efficiency is specified in the wind turbine specification using a Bladed style controller.

sima480 gener effiiciency
Figure 14. Generator Efficiency

2.9. Different damping of bending around two axes

Separate damping parameters may be given for bending around the two axes for the General and Double-symmetric cross-sections.

This allows the specification of different flap- and edgewise damping of wind turbine blades. Available for stiffness proportional Rayleigh damping.

The damping input is given the in the cross section specification and Damping specification.

The cells for Bending around the principal V-axis and Bending around the principal W-axis must be set to editable
For axis definition VW, see input specification for General cross section and Stiffness properties.
sima480 blade damping
Figure 15. Stiffness proportional damping around two axes
sima480 blade damping set to editable
Figure 16. Set to editable

3. SIMO

3.1. Catenary Line characteristics as static results

It is now possible to calculate and store line characteristics for Catenary Lines during static calculation. In the results, fairlead tension is presented as a function of the horizontal distance between anchor and fairlead.

sima480 line characteristics
Figure 17. Catenary line characteristics

4. Other

4.1. View fom side in 3D

Added view from side in context menu in 3D view.

View from side

4.2. Improved condition result presentation

Condition result now has a new view for easier inspection and interactive post processing.

Double-click the folder Results under the condition to open the results view.

There are three default views:

  • Plot

  • Statistics

  • Power Spectrum

sima480 results
Figure 18. Condition Result

It is also possible to select a time window and filter the time series. See Options tab. This has been influenced by the open source DNV tool QATS, which also can be used to post process SIMA results outside SIMA. See also How to use QATS in SIMA.

There are also several new options available when right clicking the signals in the new view:

  • Plot against each other: Select two signals and then open a cross plot in a new dialog

  • Show cross spectrum: Select two signals and show cross spectum plot

sima480 results context
Figure 19. Context menu in Result view

The signals has been removed from the navigator tree, which has added performance benefits