A new CFD-MBD wave-structure interaction model: Coupling OpenFOAM with Chrono

Interconnected multibody floating structures have gained popularity recently. The dynamic response of moored interconnected floating bodies to wave action, however, are complicated and challenging to model and analyze. To tackle the problem, a novel wave-structure-interaction (WSI) model is developed for the first time by coupling a finite volume CFD model, OpenFOAM, with Project Chrono, a multi-physics simulation engine for multibody dynamics (MBD) and finite element analysis, through linking pre-compiled dynamic libraries. This paper focuses on dynamic behavior of rigid structures restrained with a mooring system. To account for the floating body motion in the fluid solver, both mesh deformation and overset mesh methods are incorporated in the WSI model. The rigid body motion solver integrates two dynamic mooring models (MoorDyn and Moody) to simulate the seakeeping functionality. It also incorporates OpenFAST to simulate the aerodynamics, servo control and structural dynamics of floating offshore wind turbines (FOWTs). The proposed modeling framework is validated and verified against six test cases, ranging from a single floating body such as a floating wind semi-submersible platform and a point absorber wave energy converter (WEC) to a two-body hinged raft. It was found the newly developed WSI modeling framework using only the aforementioned open-source codes achieved the same level of agreement with observations as its commercial counterpart, paving the way for free high-fidelity CFD simulations for the emerging hybrid wind-wave energy and floating solar systems.