Hi Florence,
The document you attached shows a specific instance (simplification) of the general hydrodynamic axial drag formula used by HydroDyn. Here are my answers to your questions:
1 / 2) The wave kinematics (fluid particle velocities, accelerations, and dynamic pressures) used by HydroDyn’s strip theory solution are based on undisturbed wave kinematics (in the absence of the structure), regardless of whether potential-flow is enabled. The wave kinematics generated internally within HydroDyn can be regular (periodic) or irregular (stochastic) and long-crested (unidirectional) or short-crested (with wave energy spread across a range of directions). The wave kinematics can also be generated externally and used within HydroDyn. Internally, HydroDyn generates waves analytically for finite depth using first-order (linear Airy) or first- plus second-order wave theory (Sharma and Dean)with the option to include directional spreading. The second-order implementations include time-domain calculations of difference- (mean- and slow-drift-) and sum-frequency terms.
- Yes, that is correct, but each side of the plate (joint in HydroDyn) is based on the associated semisphere.
Perhaps you already saw this, but a related question about the hydrodynamic axial effects of HydroDyn was recently discussed on the forum–see: Question about axial drag in Morison.f90.
Best regards,