Solving fluid-structure interaction of flexible net structures in current and waves based on a coupled truss–porous medium model

Journal article, 2025

A numerical approach for fluid-structure interaction analysis of flow through and around rigid and flexible netting structures is developed within the OpenFOAM framework. An explicit structure solver based on a truss model is introduced to effectively solve large deformation of nets in the time domain. This solver is fully coupled with a fluid solver, where the thin net structures are modelled as porous zones. To account for the effects of drag and inertia, extra source terms estimated from a screen model are added to the volume-averaged Navier-Stokes equations. While selecting porous zone thickness has often been arbitrary in the literature, we investigate its influence on mesh convergence and demonstrate that an overly thick porous layer significantly slows convergence. A porous zone with a thickness equal to only one numerical cell is shown to provide the fastest convergence. The present numerical model has been verified and validated, with overall good agreement compared to existing experimental and numerical studies for planar and circular net structures under current and wave conditions.