A coupled BEM-FEM scheme for the interaction of water waves with multiple vertical cylinders in the presence of currents

The problem of wave propagation through arrays of vertical cylinders has been addressed by several researchers, providing useful data both by experimental and 3D numerical methods focusing on wave reflection and scattering; see Magkouris et al. (2022). For small current velocities, the problem can be approximately considered on the horizontal plane, modeled by the Helmholtz equation with variable coefficient, associated with the local wavenumber. The latter is determined by means of the local intrinsic frequency, based on the local current flow. In this work, a coupled BEM-FEM scheme is proposed for the numerical simulation of the current and wave field over multiple vertical cylinder configurations. Presented results demonstrate that the present cost-efficient modeling approach provides reasonable predictions and can be used to support the study of the hydrodynamic characteristics of more complex structures, such as coastal and harbour defense systems with porous characteristics, involving dense arrays of cylinders.