The subject of internal waves interacting with bottom topographic features in the ocean has received much attention in the past few decades. This heightened interest is mainly due to a conjecture that breaking internal waves at boundaries can be a significant source of turbulence, leading to mixing and transport in the ocean. In this paper, we present results from high-resolution three-dimensional numerical simulations of an internal wave interacting with a shelf break in a linearly stratified fluid in order to highlight the instabilities that contribute to wave breaking over topography. The results show the development of a nonlinear internal bolus (a vortex core of dense fluid) that moves upslope as a result of the interaction and subsequent breaking of the internal wave. We present details of the different stages of the interaction process that lead to wave breakdown and formation of internal boluses and their subsequent evolution toward smaller scales of motion and turbulence as they propagate onshore.

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