# Wave Drift Force - Newman’s method

Calculation of wave drift forces from wave drift force coefficients using Newman’s method (approximation). The wave drift force coefficients corresponds to the frequency diagonal of the difference-frequency quadratic transfer function. See also Simplified wave drift force model.

By checking the *Enable wave-current interaction* checkbox, the zero-current wave drift force coefficients will be modified using Aranha’s formula at the time of running a simulation, based on the actual current velocity and direction.
The corrected wave drift force coefficients can be viewed in the *wave-current correction preview*.
Note that the current velocity and direction entered in the previewer is only for the preview.
In a simulation, the actual current condition is used.
Note also that checking *Enable wave-current interaction* will only enable the excitation part of the wave-current interaction.
To also include the damping effect due to body velocities, a wave drift damping model should be added.
See also Wave-current correction of second order wave drift force and wave drift damping using an extended Aranha’s formula.

When Newman’s approximation is not valid, a full Difference-Frequency QTF should be used instead.