Evaluation of nonlinear numerical model performance on the wave propagation over a bar-trough profile beach

Abstract

Knowing the vertical structure of particle velocity is very important for the sediment transportation study. Recent development of computer resources and high performance computing enable us to use numerical models with more information in the vertical direction. In this paper, the performance of multi-layered Boussinesq model (COULWAVE) and RANS model (COBRAS-UC) on a bar-trough profile beach is examined. Results, in terms of wave heights computed by both models and the time series of the horizontal velocity (computed with COBRAS-UC model) are compared with the experimental data collected by Okamoto et al. (2008) for the test case with an incident wave of period T=1.5sec and height of H=8cm, in which the detailed vertical structure of particle velocity was measured. Both models can predict the wave height change very well until the wave breaking initiates and specially COBRAS-UC model. However, it does not agree to the experimental data after the wave breaking initiation. The COBRAS-UC model calculates the horizontal velocity near the free surface very well, but it does not agree to the experimental data in the lower section of the water column.