ocdata

Mapdl.ocdata(val1='', val2='', val3='', val14='', **kwargs)

Defines an ocean load using non-table data.

APDL Command: OCDATA

Parameters
  • val1 – Values describing the basic ocean load or a wave condition.

  • val2 – Values describing the basic ocean load or a wave condition.

  • val3 – Values describing the basic ocean load or a wave condition.

  • . () – Values describing the basic ocean load or a wave condition.

  • val14 – Values describing the basic ocean load or a wave condition.

Notes

The OCDATA command specifies non-table data that defines the ocean load, such as the depth of the ocean to the mud line, the ratio of added mass over added mass for a circular cross section, or the wave type to apply. The terms VAL1, VAL2, etc. are specialized according to the input set required for the given ocean load.

The program interprets the data input via the OCDATA command within the context of the most recently issued OCTYPE command.

Input values in the order indicated.

This command is also valid in PREP7.

You can define the following ocean data types:

For a better understanding of how to set up a basic ocean type, see Figure: 5:: Basic Ocean Data Type Components .

DEPTH – The depth of the ocean (that is, the distance between the mean sea level and the mud line). The water surface is assumed to be level in the XY plane, with Z being positive upwards. This value is required and must be positive.

MATOC – The material number of the ocean. This value is required and is used to input the required density. It is also used to input the viscosity if the Reynolds number is used (OCTABLE).

KFLOOD – The inside-outside fluid-interaction key:

For beam subtype CTUBE and HREC used with BEAM188 or BEAM189 and ocean loading, KFLOOD is always set to 1.

Cay – The ratio of added mass of the external fluid over the mass of the fluid displaced by the element cross section in the y direction (normal). The added mass represents the mass of the external fluid (ocean water) that moves with the pipe, beam, or link element when the element moves in the element y direction during a dynamic analysis.

If no value is specified, and the coefficient of inertia CMy is not specified (OCTABLE), both values default to 0.0.

If no value is specified, but CMy is specified, this value defaults to Cay = CMy - 1.0.

If this value should be 0.0, enter 0.0.

Caz – The ratio of added mass of the external fluid over the mass of a cross section in the element z direction (normal). The added mass represents the mass of the external fluid (ocean water) that moves with the pipe, beam, or link element when the element moves in the element z direction during a dynamic analysis.

If no value is specified, and Cay is specified, this value defaults to Cay.

If no value is specified, and the coefficient of inertia CMz is not specified (OCTABLE), both values default to 0.0.

If no value is specified, but CMz is specified, this value defaults to Cay = CMz - 1.0.

If this value should be 0.0, enter 0.0.

Cb – The ratio of buoyancy force used over buoyancy force based on the outside diameter and water density. Accept the default value in most cases. Adjust this option only when you must account for additional hardware (such as a control valve) attached to the pipe exterior. A non-default value may lead to small non-physical inconsistencies; testing is therefore recommended for non-default values.

If no value is specified, this value defaults to 1.0.

If this value should be 0.0 (useful when troubleshooting your input), enter 0.0.

Zmsl – A vertical offset from the global origin to the mean sea level. The default value is zero (meaning that the origin is located at the mean sea level).

Two example cases for Zmsl are:

A structure with its origin on the sea floor (Zmsl = DEPTH).

A tidal change (tc) above the mean sea level (Zmsl = tc, and DEPTH becomes DEPTH + tc)

Ktable – The dependency of VAL1 on the OCTABLE command:

Figure: 5:: : Basic Ocean Data Type Components

KWAVE – The incident wave type:

THETA – Angle of the wave direction θ from the global Cartesian X axis toward the global Cartesian Y axis (in degrees).

WAVELOC (valid when KWAVE = 0 through 3, and 101+) – The wave location type:

SPECTRUM (valid when KWAVE = 5 through 7) – The wave spectrum type:

KCRC – The wave-current interaction key.

Adjustments to the current profile are available via the KCRC constant of the water motion table. Typically, these options are used only when the wave amplitude is large relative to the water depth, such that significant wave-current interaction exists.