Transformation of Large Amplitude Internal Waves Over a Shelf

N. V. Gavrilov, V. Yu. Liapidevskii, Z. A. Liapidevskaya

The propagation of finite amplitude internal waves over an uneven bottom is considered. One of the specific features of the large amplitude internal waves is the ability of the waves to carry fluid in the «trapped core» for a long distance. The velocity of particles in the «trapped core» is very close and, even, exceeds the wave speed. Such waves are detected in different parts of seas and oceans as internal waves of depression and elevation as well as short intrusions at interfaces. Laboratory experiments on the generation, interaction and decay of solitary waves in a two-layer fluid are discussed. Analytical and numerical solutions describing the evolution of internal waves in a shelf zone are constructed by the three-layer shallow water model. Laboratory investigations of the different types of internal waves (bottom, subsurface and interlayer waves) are demonstrated, that the model can be effectively applied to the numerical solution of unsteady wave motions, and the travelling waves, which can be found from the model in rather simple form, give the realistic form and governing parameters of internal waves in laboratory and field observations. The basic features of the large amplitude solitary waves and nonlinear wave trains evolution over a shelf can be represented by the model.

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