1. Growth - Specification of marine growth profile

1.1. Data group identifier, one input line

NEW COMPonent GROWth

1.2. Component type identifier, one input line

CMPTYP-ID    NGRLEV

  • CMPTYP-ID: character(8): Component type identifier

  • NGRLEV : integer: Number of growth levels

1.3. Growth profile, one input line per growth level, i.e. NGRLEV input lines

GRLEV GRTH GRDENS

  • GRLEV: real: Z coordinate of level given in global coordinate system \(\mathrm {[L]}\)

  • GRTH: real: Growth thickness \(\mathrm {[L]}\)

  • GRDENS: real: Growth density at this level \([\mathrm {M/L^3}]\)

The input lines must be given for decreasing values of GRLEV; i.e. with increasing depth. Linear interpolation will be used to find values at intermediate levels. Outside the specified range, the growth thickness is set to zero, i.e. for Z > GRLEV(1) and Z < GRLEV(NGRLEV) the thickness is zero.

Marine growth will be applied to elements with CRS0, CRS1, CRS2 and CRS7 cross-sections.

The volume loads will be modified if the external area is non-zero. A circular cross-section is assumed and the thickness of the marine growth is added to the radius corresponding to the initial external area.

The Morison quadratic drag and added mass coefficients will be modified if the hydrodynamic diameter is non-zero. For CRS2 and CRS7 cross-sections, the diameter of a circular cross-sections with the same external area is used as the hydrodynamic diameter.

The added mass coefficients will be scaled by the square of this ratio.

The quadratic drag coefficients will be scaled by the ratio of the updated to the initial hydrodynamic diameter. Linear drag coefficients will not be modified.

The correction of mass, hydrodynamic diameter, added mass- and drag coefficients:

  • Mass per length AMS including marine growth

    • \(\mathrm {AMS_{growth}=AMS+(AE_{growth}-AE){\cdot}GRDENS}\)

  • Hydrodynamic diameter including marine growth

    • \(\mathrm {DH_{growth}=DH+2\cdot GRTH}\)

  • Added mass coefficients

    • \(\mathrm {CAX\cdot(\frac{DH_{growth}}{DH})^2}\)

    • \(\mathrm {CAY\cdot(\frac{DH_{growth}}{DH})^2}\)

    • \(\mathrm {CAZ\cdot(\frac{DH_{growth}}{DH})^2}\)

  • Quadratic drag coefficients CDX,CDY and CDZ

    • \(\mathrm {CDX\cdot(\frac{DH_{growth}}{DH})}\)

    • \(\mathrm {CDY\cdot(\frac{DH_{growth}}{DH})}\)

    • \(\mathrm {CDZ\cdot(\frac{DH_{growth}}{DH})}\)

Marine growth will be applied if it is specified as a load group in STAMOD. The load incrementation procedure is specified as input to the STAMOD module.

Currently, only one growth profile may be given.
Specification of marine growth profile cannot be used in combination with drag amplification.