Role of Wave Pressure in Bedload Sediment Transport

Abstract

Loading from ocean waves propagating in shallow water will normally set some of the bottom sediment in motion, resulting in well-known and far-reaching consequences. In this study, we highlight the role of wave pressure in some of the physical processes taking place at and near the seafloor interface during the propagation of a water wave above. Poroelasticity is used to model the strain in the seabed. Saffman’s slip boundary condition at a fixed porous boundary is extended for a porous bed that is both deformable as well as erodible. The granular flow of the fluidized sediment on the seafloor is modeled as a viscoelastic fluid, with a frequency-dependent complex-viscosity coefficient. A Coulomb-type failure criterion is employed to quantify the magnitude of fluidization under the combined wave shear-and-pressure loading. Nonlinear boundary-layer equations are then solved for the motion of the fluidized sediment and hence provide an estimation of bedload transport by water waves.