Modeling of Hydrodynamics and Sedimentary Processes Related to Unbroken Progressive Shallow Water Waves

Abstract

This paper reports on numerical modeling designed to examine hydrodynamics and sedimentary processes related to unbroken progressive waves propagating in nearshore areas. The first part of the paper concerns microscale processes developing in the near-bed boundary layer. At the first stage of the study a second order turbulence closure model is applied. The numerical model is tested against experimental data and applied to the prediction of a near-bed How of sediment in suspension induced by linear and nonlinear waves. For mild wave-dominated coastal environments with typically low volumetric sediment concentrations (c = 10^-3 – 10^-4) the model predicts a weak influence of sediment particles on the mean flow velocities. Therefore, at the second stage of the study, the modeling procedure is decoupled, separating the flow dynamics from diffusion and advection of sediment. A simpler, analytical closure model is applied and its results are tested against the second-order closure model, showing a satisfactory agreement. The second part of the paper is devoted to macroscale cross-shore processes. The simple analytical bottom boundary layer model is incorporated into the framework of a two-dimensional sediment transport and morphodynamical model of the outer shoreface of coastal zones subject to moderate-energy wind-dominated conditions.