# Mean Drift calculations in HydroDyn

Dear all,

I have been modifying the code of HydroDyn (openfast v.2.2) to improve some validation results of FOWT.

I would like to know if the frequency step-size term is included in the Mean Drift force calculations routines.

In the code WAMIT2.f90, line 772 there is the following comment before the sub-routine:

Note that this is !! is a numerical integral, so the \f$\Delta\omega \f$ term is necessary.

But later I do not see that term included in the final summation of the force (line 1165) and I am not sure if is it missing or is it included in other part of the code.

Thanks

Felipe