The Regular Wave object is used for Time Response analyses. Regular Waves can only be applied when the Analysis Type under the Time Response Analysis Setting object is set to Regular Wave Response (rather than the default value of Irregular Wave Response).
To add a Regular Wave:
Select the Hydrodynamic Response object in the tree view.
Right-click the Hydrodynamic Response object and select Insert > Regular Wave, or click on the Regular Wave icon in the Analysis toolbar.
Set Wave Type to Airy Wave Theory, Stokes 2nd Order Wave Theory, or Stokes 5th Order Wave Theory for the calculation of the Froude-Krylov forces. Airy Wave Theory is not recommended for modeling big waves; Stokes 5th Order Wave Theory is typically suited to shallow water situations. Enter the Direction and Amplitude of the wave. The direction is shown in the graphics with an arrow (light blue).
The other parameters to define the Regular Wave depend on the Wave Type. For Airy or Stokes 2nd Order waves, enter a Period or Frequency for the wave. The period/frequency in general should be within the range of that in the Hydrodynamic Diffraction analysis.
Note: Both Frequency and Period are enabled as parameters, but it is only possible to parameterize one of these at a time. For example, if you set Period as a parameter, the Frequency field will not longer be visible; to set Frequency as a parameter, Period must be removed as a parameter first.
For Stokes 5th Order waves, the wave definition is controlled by 6 parameters: Period, Wavelength, Still Water Depth, Mean Water Depth, Uniform Current, and Volume Flux. These are interdependent, meaning that you can define any 3 parameters at once; the Define By option allows you to choose which parameters to set. For example, when Define By is selected as Wavelength, Still Depth, Current, you must enter values for Wavelength, Still Water Depth and Uniform Current. The Period, Mean Water Depth and Volume Flux values are calculated from your entered data, and displayed (read-only) for your reference. For more information, see Fifth Order Stokes Wave.
The wave ramp is introduced to reduce the transient motion of the structure at the beginning of a time domain analysis. The wave ramp will take effect from t=0.0 to t = tw, during which time a wave ramp factor f (0.0 < f < 1.0) will be calculated and then used to multiply the incident wave amplitude. The wave ramp factor f is
It can be seen that at t=0, the factor is 0.0 and at t=tw, the factor is 1.0. If Ramping Method is set to Program Controlled, tw will default to the wave period. Alternatively, change Ramping Method to Manual Definition to allow the Ramping Time to be set to the desired time tw, or set Ramping Method to No Ramping to turn the wave ramp off.