The Hydrodynamic Pressure Add-on is designed to facilitate the transfer of hydrodynamic pressures and Morison loads calculated in a Hydrodynamic Diffraction or time domain Hydrodynamic Response system to a Static Structural finite element analysis.

When mapping from a Hydrodynamic Diffraction system the hydrodynamic pressure terms are linear (first order), and include incident (Froude-Krylov), diffracted, radiated and hydrostatic-varying components. Hydrostatic pressure may be added if required. The wave direction and frequency pairs are selected from those included in the Hydrodynamic Diffraction calculation; an incident wave amplitude is also specified. The load mapping can be carried out either at a single specified wave phase angle, over multiple phase angles covering the whole of the wave cycle, or for real and imaginary components (in linear cases). Similarly, the mapping may be performed either for a single frequency/direction pair or, where the Hydrodynamic Diffraction system includes multiple Wave Frequencies or Wave Directions, over some or all of those frequency/direction pairs. The summed pressure terms are mapped onto triangular and quadrilateral panel elements in the Static Structural mesh, either by interpolation, or by direct evaluation of the diffracting panel source strengths at the Static Structural mesh node positions.

The Hydrodynamic Pressure Add-on also allows the Hydrodynamic Diffraction first order (Froude-Krylov, added mass) and second order (viscous drag) forces acting on Line Bodies (element types BEAM188 and PIPE288) to be included in a Static Structural analysis. The effect of ocean current may be accounted for in the drag calculation.

For pressure mapping from a time domain Hydrodynamic Response system, the hydrodynamic pressure terms are linear for the diffracted and radiated components and nonlinear for the incident (Froude-Krylov) and hydrostatic components. These latter terms are estimated under the instantaneous wave surface in the time domain calculation. The first order (Froude-Krylov, added mass) and second order (viscous drag) forces on Line Bodies, as well as the forces and moments on Morison disc elements, can also be mapped from the hydrodynamic model. The pressure mapping can be carried out at a single specified time step, over a range of time steps, or for all time steps included in the time domain Hydrodynamic Response pressure output. The total pressure terms are mapped by interpolation on to triangular and quadrilateral panel elements in the Static Structural mesh.

The Hydrodynamic Pressure Add-on allows the instantaneous cable forces, joint forces/moments and tether forces/moments, calculated in a time domain Hydrodynamic Response system, to be mapped on to selected locations of the structural model.

For both Hydrodynamic Diffraction and time domain Hydrodynamic Response pressure mapping, the resultant translational and rotational accelerations about the structure center of gravity are determined for the balance of inertial loads in the Static Structural analysis. Standard Earth Gravity is added to the translational accelerations where hydrostatic pressure is included in the mapping.