Seabed bathymetry and friction modeling in MoorDyn

This paper presents the implementation and verification of a seabed bathymetry feature friction to open-source, lumped-mass mooring system dynamics modeler, MoorDyn, which is part National Renewable Energy Laboratory’s aero-hydro-servo-elastic simulation tool, OpenFAST. Variations in slope, as well frictional effects lines moving along seabed, will affect line tensions floating platform consequent response. These new features are especially relevant for modeling systems deep-water coastal areas where depth can change significantly over an entire footprint. The models rectangular grid variable water depths place existing, uniform MoorDyn. force primarily represented Coulombic force, or product kinetic coefficient contact normal with ability differentiate between transverse axial motion node on any grid. capabilities were tested by running MoorDyn OpenFAST simulations variety environmental conditions; resulting fairlead tensions, kinematics verified against equivalent OrcaFlex simulations. results match closely, meaning verified, increase overall fidelity FAST.Farm