OCTABLE

OCTABLE, VAL1, VAL2, VAL3, VAL4, VAL5, VAL6, VAL7
Defines an ocean load using table data.

Valid Products: Pro | Premium | Enterprise | PrepPost | Solver | AS add-on

VAL1, VAL2, VAL3, . . . , VAL6

Values describing the basic ocean load, a current condition, or a wave condition.

Notes

The OCTABLE specifies table data that defines the ocean load. 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 OCTABLE command within the context of the most recently issued OCTYPE command.

There is no limit to the number of data input.

Input values in the order indicated.

This command is also valid in PREP7.

You can define the following ocean data types:

Ocean Data Type: Basic (OCTYPE,BASIC)

Basic ocean data to provide in the value fields:
IndVar, --, CDy, CDz, CT, CMy, CMz
where
IndVar = Independent variable for the table inputs. This value is dependent on the Ktable value specified via the OCDATA command. If Ktable = Z, enter this value in descending order on each OCTABLE command. If Ktable = RE, enter this value field in ascending order.
-- = Reserved.
CDy = Drag coefficient in the element y direction (normal).
CDz = Drag coefficient in the element z direction (normal). This value defaults to CDy.
CT = Drag coefficient in the element x direction (tangential).
CMy = Coefficient of inertia in the element y direction. If no value is specified, and Cay is specified, this value defaults to Cay + 1.0. If neither this value nor Cay is specified, both values default to 0.0.
CMz = Coefficent of inertia in the element z direction. If no value is specified, and CMy is specified on the same OCTABLE command, this value defaults to CMy. If neither this value nor CMy is specified, and Caz is specified, this value defaults to Caz + 1.0. If neither this value nor Caz is specified, both values default to 0.0.

Ocean Data Type: Current (OCTYPE,CURR)

Current data to provide in the value fields:
Dep, W, Th, Te
where
Dep = Depth of the drift current being input. Input these values in ascending order from one command to the next.

  • If the current is constant, only one OCTABLE command is necessary and Dep is not required.

  • For waves, the current profile is stretched or compressed linearly up to 10 percent.

  • The first Dep value (representing the mean sea level) must be zero. The last Dep value (representing the mud line) must be equal to the DEPTH value input on the OCDATA command.

  • The Cartesian Z values used to locate nodes, etc. decrease as one moves from the ocean surface to the sea floor, but the Dep values increase. See Figure 7: Basic Ocean Data Type Components .

  • Dep is not affected by changes to Zmsl on the OCDATA command, as that value simply relocates the origin.

W = Velocity of the drift current at this location.
Th = Angle of the drift current from the global Cartesian X axis toward the global Cartesian Y axis (in degrees) at this location.
Te = Temperature at this location.

Ocean Data Type: Wave (OCTYPE,WAVE)

When specifying an ocean wave type, issue the OCTABLE command to input either wave location data or wave spectrum data.

    Wave Location Input Data

    Wave location data to provide in the value fields (valid only when KWAVE = 0 through 3, or 8, on the OCDATA command):
    H, T, Ps, L, NORDER, KPRCO
    where
    H = Wave height (peak-to-trough).
    T = Wave period.
    Ps = Phase shift (in degrees)
    L = Wavelength. An optional value used only when KWAVE = 0 or 1 (and ignored for all other KWAVE types).
    NORDER = Order used by stream function wave theory (KWAVE = 3). This value is optional.
    KPRCO = Key for printing (1) or not printing (0 and default) the calculated dimensionless coefficients of the stream function wave theory (KWAVE = 3). This value is optional.

    Hints for Wave Location Input:

    • The TIME command is not used, except perhaps to identify the load case.

    • The phase shift (Ps) determines the wave position (that is, the point at which the load is to be applied).

    • When using the Stokes fifth-order (KWAVE = 2) or stream function (KWAVE = 3) wave type, issue only one OCTABLE command.

    • The valid range of the order of the stream function (NORDER) is 3 through 50. If no value is specified, the program determines a value automatically.

    • When using the diffracted wave type (KWAVE = 8), an OCREAD command is also required to read in the hydrodynamic data from the hydrodynamic analysis.

    Wave Spectrum Input Data

    Wave spectrum data to provide in the value fields (valid only when KWAVE = 5 through 7 on the OCDATA command):
    SPECTRUM = 0 (Pierson-Moskowitz spectrum)
    HS, TP, NWC
    where
    HS = Significant wave height of the spectrum.
    TP = Peak period for the spectrum.
    NWC = Number of wave components (1 NWC 1000) to model the spectrum. (Default = 50.)
    SPECTRUM = 1 (JONSWAP spectrum)
    HS, TP, GAMMA, NWC
    where
    HS = Significant wave height of the spectrum.
    TP = Peak period for the spectrum.
    GAMMA = Peak enhancement factor for the spectrum. (Default = 3.3.)
    NWC = Number of wave components (1 NWC 1000) to model the spectrum. (Default = 50.)
    SPECTRUM = 2 (User-defined spectrum)
    w, s, NWC
    w = Angular frequency (rad/s).
    s = Spectral energy density (Length2 / (rad/s))
    NWC = Number of wave components (1 NWC 1000) to model the spectrum. (Default = 50.)

    Hints for Wave Spectrum Input:

    • When defining a Pierson-Moskowitz or JONSWAP spectrum (SPECTRUM = 0 or 1, respectively, on the OCDATA command), issue only one OCTABLE command.

    • When defining a Pierson-Moskowitz or JONSWAP spectrum for Shell new wave (KWAVE = 6 on the OCDATA command), HS is calculated from the maximum wave crest amplitude (AMPMAX on the OCDATA command) if no value is specified. For further information, see Hydrodynamic Loads in the Mechanical APDL Theory Reference.

    • For a user-defined spectrum (SPECTRUM = 2 on the OCDATA command), issue an OCTABLE command for each frequency data point defining the spectrum. Specify the frequency data in ascending order. The number of wave components (NWC) is required on the first OCTABLE command only.

    Ocean Zone Type: Component or Z-Level (OCZONE,COMP/ZLOC)

    An ocean zone is a local space where you can override global ocean-loading parameters.

    Ocean zone data to provide in the value fields:

    Z, --, CDy, CDz, CT, CMy, CMz, Mbio, Tbio

    where

    Z = Z level for the coefficients specified on this command.
    -- = Reserved.
    CDy = Drag coefficient in the element y direction (normal).
    CDz = Drag coefficient in the element z direction (normal). This value defaults to CDy.
    CT = Drag coefficient in the element x direction (tangential).
    CMy = Coefficient of inertia in the element y direction.
    CMz = Coefficient of inertia in the element z direction. This value defaults to CMy.
    Mbio = Material ID of biofouling.
    Tbio = Thickness of biofouling.

    Ocean Zone Type Usage Notes

    Ocean zone values specified via the OCTABLE command override global ocean-loading parameters.

    Arguments not specified default to the global values specified for the basic ocean type (OCTYPE,BASIC). Therefore, the relationship between Ca and CM values (Ca = CM - 1.0) is not applied to ocean zones.

    The OCTABLE command is not valid for a pipe-type ocean zone (OCZONE,PIP).

    Menu Paths

    This command cannot be accessed from a menu.