Focusing of Internal Waves upon Oscillations of Torus-Like Bodies in a Uniformly Stratified Fluid

This paper presents an experimental study of the focusing of internal waves emitted by horizontal oscillations of a torus-like body in linearly stratified fluid. The body had a circular generatrix and an elliptical backbone curve connecting the centers of the generatrices. Experimental data on the internal wave amplitude distribution in the vicinity of an axisymmetric oscillating torus are compared to linear theory estimates in the thin body approximation. It is shown that, if waves are generated by nonaxisymmetric wave generators, the amplitude in the focusing zone is smaller, which is caused by differences in both total emission power and focusing zone structure. We have constructed isosurfaces of experimentally measured wave amplitudes in the focusing zone and compared the data to ray theory predictions.