Fully coupled two-dimensional numerical simulation of wave interaction with an elastic wall in a narrow gap

Abstract

Narrow-gap resonance is commonly investigated under rigid-wall assumptions, although deformable boundaries occur in many confined-water systems. This study aims to clarify how elastic-wall deformation and the geometry of the bottom passage affect the coupled hydrodynamic and structural responses of an open-top confined-water system. A two-dimensional strongly coupled partitioned finite volume method–finite element method model, implemented using OpenFOAM, CalculiX, and preCICE, is validated against published hydroelastic results and wave-flume measurements. Wall stiffness and draft are varied to evaluate the local flow, confined free-surface motion, wave reflection and dissipation, hydrodynamic loading, wall displacement, and response phase. The results show that decreasing wall stiffness increases wall deformation and weakens the high-velocity region beneath the wall, thereby reducing the free-surface oscillation inside the confined region. The near-rigid and moderately elastic cases retain a low-reflection–high-dissipation response within a similar frequency range, whereas the most flexible case weakens this feature, with a higher reflection minimum and a lower dissipation maximum. The most flexible wall exhibits reduced load amplitudes at intermediate and higher frequencies, together with a more pronounced phase lag. Reducing the wall draft enlarges the bottom passage, shifts the reflection minimum and dissipation maximum toward higher frequencies, and decreases both load and displacement amplitudes. The results provide guidance for selecting wall stiffness and draft in flexible wave-energy devices and elastic coastal-protection components.