Pengzhi Lin

A numerical study of breaking waves in the surf zone

This paper describes the development of a numerical model for studyingn the evolution of a wave train, shoaling and breaking in the surf zone. The model solvesn the Reynolds equations for the mean (ensemble average) flow field and the k –e equations for the turbulent kinetic energy, k , and the turbulence dissipationn rate, e. A nonlinear Reynolds stress model (Shih, Zhu & Lumley 1996) is employed to relaten the Reynolds stresses and the strain rates of the mean flow. To track free-surface movements,n the volume of fluid (VOF) method is employed. To ensure the accuracy of eachn component of the numerical model, several steps have been taken to verify numericaln solutions with either analytical solutions or experimental data. For non-breakingn waves, very accurate results are obtained for a solitary wave propagating over a longn distance in a constant depth. Good agreement between numerical results and experimentaln data has also been observed for shoaling and breaking cnoidal waves on a slopingn beach in terms of free-surface profiles, mean velocities, and turbulent kineticn energy. Based on the numerical results, turbulence transport mechanisms under breakingn waves are discussed.

Turbulence transport, vorticity dynamics, and solute mixing under plunging breaking waves in surf zone

Plunging breaking waves generate turbulence and vorticity, which are of great importance for the solute and sediment transport in surf zone. In this paper the complex breaking processes are simulated by using an accurate numerical model that solves the Reynolds equations for the mean flow and modified k-e equations for the turbulence field. A solute transport model is employed to investigate the solute mixing under plunging waves. After validation of the numerical model by comparing numerical results with available experimental data, the numerical model is further utilized to study the detailed mechanisms of turbulence transport and vorticity dynamics. The differences between spilling and plunging breaking waves are discussed. The impact of the wave breaking on solute mixing in the surf zone is also examined.

Generation and evolution of edge-wave packets

In this paper the generation and evolution of an edge-wave packet are studied experimentally and numerically. In the laboratory an edge-wave packet is first generated on a sloping beach by a hinge-type wave-maker. Both the free surface displacement and velocity field are measured along several on-offshore cross sections. Numerical results are also obtained by solving the linear shallow-water wave equations and are compared with experimental data. Numerically predicted wave evolution characteristics are in good agreement with those shown by laboratory data. Analyses of the wave amplitude density spectra of both numerical solutions and experimental data show that wave packets are indeed trapped in the nearshore region and consist of a mixture of Stokes and higher-mode edge waves. Furthermore, the Stokes mode dominates in the low frequency range. Two additional wave-maker designs, i.e., the piston-type and the reverse hinge-type, are investigated numerically. Away from the wave-maker the wave forms (time his...