Coupled computational fluid and multi-body dynamics suspension boat modeling

Abstract

Multiphysics modeling, code development, and validation by full-scale experiments is presented for hydrodynamic/suspension-dynamic interactions of a novel ocean vehicle, the Wave Adaptive Modular Vessel (WAM-V). The boat is a pontoon catamaran with hinged engine pods and elevated payload supported by suspension and articulation systems. Computational fluid dynamics models specific to WAM-V are developed which include hinged pod dynamics, water-jet propulsion modeling, and immersed boundary method for flow in the gap between pontoon and pod. Multi-body dynamics modeling for the suspension and upper-structure dynamic is developed in MATLAB Simulink. Coupled equations of motion are developed and solved iteratively through either one-way or two-way coupling methods to converge on flow-field, pontoon motions, pod motions, waterjet forces, and suspension motions. Validation experiments include cylinder drop with suspended mass and 33-feet WAM-V sea-trials in calm water and waves. Computational results show that two-way coupling is necessary to capture the physics of the interactions. The experimental trends are predicted well and errors are mostly comparable to those for rigid boats, however, in some cases the errors are larger, which is expected due to the complexity of the current studies. Ride quality analyses show that WAM-V suspension is effective in reducing payload vertical accelerations in waves by 73% compared to the same boat with rigid upper-structure.