Wave Drift Damping - Newman’s method

Wave drift damping is the damping force due to the velocity dependency of the second order wave drift forces, see also theory: Wave drift damping (Newman’s method).

Wave drift damping forces are calculated from frequency dependent wave drift damping coefficients, which can come from different sources, as selected by the From dropdown menu:

  • Input - The wave drift damping coefficients are provided as direct input. Normally, these coefficients are computed by WADAM and imported from the SIF file.

  • QTF - The wave drift damping coefficients are computed from Aranha’s formula, which uses zero-current wave drift force coefficients extracted from the diagonal of the full Difference-Frequency quadratic transfer function (QTF).

  • Wave Drift Force - The wave drift damping coefficients are computed from Aranha’s formula, which uses the zero-current Wave Drift Force coefficients.

Two alternatives are available as selected by the Force Calculation radio buttons:

  • Absolute body velocity - Linearization point taken at the current velocity. This option is consistent with Aranha’s method.

  • Body velocity relative to the current - Linearization point taken at zero relative velocity. This option is consistent with wave drift damping coefficients computed by WADAM.

The background for the two alternatives are further described in the theory manual: Wave drift damping (Newmans method).