Mesh-based nonlinear Froude-Krylov and hydrostatic load calculation in HydroDyn

[luwang00]

This PR is not ready to be merged.

Feature or improvement description
This PR adds mesh-based nonlinear Froude-Krylov and hydrostatic load calculation in HydroDyn for the potential-flow bodies. This is still a work in progress with only basic functionality implemented. More information to come.

Initially, the implementation will only support ASCII STL files. The algorithm only supports triangular patches. Clipping of the triangular patches at the instantaneous waterline is included for fast convergence on coarse mesh.

For potential-flow bodies with nonlinear FK and hydrostatics enabled. HydroDyn requires the *.3sc file from WAMIT, which only contains the linear scattering loads to avoid double-counting the Froude-Krylov part. It also automatically zeros out the hydrostatic loads from PtfmVol0 and the hydrostatic stiffness matrix. Any second-order potential-flow loads are also zeroed out. Note that for NBodyMod=1 (coupled potential-flow bodies), nonlinear Froude-Krylov and hydrostatics must be enabled or disabled for all bodies together. For decoupled bodies (NBodyMod=2 or NBodyMod=3), nonlinear FK and hydrostatics can be selectively enabled for some bodies. The new features are currently incompatible with generalized degrees of freedom with NAddDOF>0.

Still requires

• New output channels
• HydroDyn summary file update
• Documentation update
• r-test input file update
• HD Jacobian performance optimization

Impacted areas of the software
HydroDyn

Generative AI usage
Co-authored-by: Google Gemini gemini@google.com

Test results, if applicable
Requires input file changes, but should not affect r-test results if the new features are not used.

• r-test branch merging required