Numerical modeling of boundary layer flow under shoaling and breaking waves

Abstract

To investigate the turbulent boundary layer under graphics. shoaling and breaking waves, an existing numerical model was utilized, and in turn a comparison was made with laboratory measurements. The numerical solution to the problem of a wave-induced turbulent boundary layer consistent with the first order wave theory was used, and the equations for turbulent closure were presented. There were three cases that were considered with different assumptions based on the relative importance of the production, diffusion, and dissipation of turbulence. The first order solution was compared with experimental results. Using a Discrete Fourier Transform, a quantitative representation of the solution such as amplitudes and phases was obtained. A sensitivity analysis of the model with respect to the specified von KirmØn constant and bottom roughness height was conducted. However, since the numerical model did not give satisfying results seaward of the breaking location, it was concluded that the model would not be suitable for predicting the turbulent boundary layers under breaking waves in the surf zone. The comparisons indicated that the model would worked well for waves with a longer period, it did not work well for experimental measurements used in this study with a shorter period.