Novel computational fluid dynamics-finite element analysis solution for the study of flexible material wave energy converters

The use of flexible materials for primary mover and power take-off of wave energy converters (WECs) has attracted considerable attention in recent years, owing to their potential to enhance the reliability, survivability, and wave energy conversion efficiency. Although some reduced order models have been used to study the fluid-structure interaction (FSI) responses of flexible wave energy converters (fWECs), they are somehow inappropriate due to their limited accuracy and applicability span. To gain a deeper understanding of the physical mechanisms in fWECs, a high-fidelity approach is required. In this work, we build up a fluid-structure interaction analysis framework based on Computational Fluid Dynamics (CFD) and a Finite Element Analysis (FEA) method. The incompressible viscous flow is resolved by solving three-dimensional unsteady Navier-Stokes equations with a finite volume approach. The structure dynamics are solved by a finite element method, taking the nonlinear behaviour of flexible material into consideration. A strong coupling strategy is utilized to enhance the numerical stability and convergence of the iterative process. We demonstrate the present FSI tool is able to provide rich flow field information and structural response details, such as the velocity, pressure, structural stress distribution, etc. This is illustrated through several case studies, including two types of fWECs. The unsteady wave-structure-interaction, and the associated nonlinear phenomena, are also accurately captured by this tool.