Numerical Modelling of Wave Induced Seabed Response

Abstract

The excess pore pressure induced by the dynamic wave-induced pressure fluctuations on the seabed is a major factor causing seabed instability. This study critically examines the mechanism of wave-induced soil response, including pore pressure using an integrated model which incorporates two sub-models – the fluid model and Biot's poro-elastic model. The effects of the wave motion in the seabed and the fluid exchange at the interface between the fluid and solid domain is considered. The wave motion is described by the Volume Averaged Navier-Stokes (VARANS) equations with air-water interface traced by the Volume of Fluid (VOF) method. The behaviour of the porous seabed is governed by partially dynamic Biot's equations (u-p model). The finite volume method is used to solve the VARANS and Biot's equation in the open-source OpenFOAM® framework. A one-way coupling algorithm integrates the wave model and the seabed model. The fluid and the u-p models are validated against available experimental data to assess their capability in simulating wave-seabed interaction problems. A good agreement has been obtained between the numerical values and the experimental measurements in the validation study. A case study of a seabed subjected to nonlinear waves has been considered in the study. The seabed is assumed to be isotropic and homogeneous. A parametric study has been conducted to investigate the influence of wave parameters such as wave height, and the time period and soil characteristics such as permeability and degree of saturation on the wave-induced seabed response.