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Free surface stretching method
In static analysis, the free surface is assumed to be an horizontal plane located at Z=0. In dynamic the wave elevation \(\eta\) is calculated as the sum of all the wave components elevation.
The Wheeler stretching method is used to derive the wave velocity and acceleration at Z= \(\eta\) from the values initially given by the linear theory at Z = 0.
If h is the mean water depth, Z is changed in Z' as follows :
For an irregular wave, a correction is introduced into the Wheeler model. The new model is called Wheeler+. According to this model, for the i-th wave component, the following change is performed :
Even the bottom has a constant slope or a complex shape for contact or friction purposes, the wave kinematics is determined using a constant mean water depth h in the wave dispersion equation.
Warning
The Wheeler+ model has been introduced in the version V4R1 since inconsistent results on though and crest velocities have been exhibited with the previous method.
The current is defined by its speed and direction at different levels. Outside the definition domain the current is kept constant i.e. in the wave crests the current speed is given by the value at Z=0.
Note
when the seabed is not flat, the current profile remains constant in space and does not follows the actual mudline's shape.
