ABSTRACT

The scope of this paper is to show the results obtained for simulating 3D plunging breaking waves by solving the Navier-Stokes equations in air and water, coupled with a subgrid scale turbulence model. The breaking processes including overturning, splash-up and breaking induced vortex-like motion beneath the surface are presented and discussed. Plunging breaking waves have been simulated in periodic domains and compared with previous published works. We found a very good agreement with the general description we could find in the literature concerning the breaking processes.

INTRODUCTION

The problem of wave breaking has been studied a lot in the last two decades, as it has implications in coastal engineering and oceanography. Many references can be found in the important following reviews: Peregrine (1983), Battjes (1988), Svendsen et al. (1996) and Christensen et al. (2002). Since breaker types are not only visually different in shape, but also in the kind of vortices they induce and in the way turbulence will affect sediment transport, it is important to investigate and to demonstrate the ability of the numerical tool to accurately describe the breaking phenomenon, considering the two media, air and water. This is indeed a great difference between previous published works and the study we present in this paper. We have already obtained promising results (Lubin, 2003a), assuming that three dimensional simulation without a turbulence model would give a good indication of the processes which happen when waves break. The interface tracking is achieved by a Lax-Wendroff TVD scheme (Vincent and Caltagirone, 2000), which is able to handle with interface reconnections. The interest of this approach is to provide a complete description of free surface and velocity evolutions in the two phases, which must lead to the understanding of turbulent flow structures thanks to the introduction of a turbulence model.

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