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Internal waves play important role in the dynamics of atmosphere and ocean, being responsible for significant transport of momentum and energy through stratified fluids. Radiation and diffraction of internal waves significantly affect the motions of deep submersibles, submerged buoys and moored structures. In the case of a constant vertical density gradient (uniform stratification) theoretical description of internal-wave generation by an oscillating body is complicated by a non-trivial dispersion relation, which relates the directions of group and phase velocities with the oscillation frequency and yields no information on the spatial structure of internal-wave beams. Another complication is that linear theory of ideal uniformly stratified fluid predicts infinite displacements of fluid particles along characteristic lines tangent to the oscillating body. The talk will present analytical and experimental studies of oscillations of bodies in stratified fluids, with particular emphasis on evaluation of hydrodynamics loads, similitude criteria for the force coefficients, relation of frequency- and time-domain solutions, and optical measurements of internal waves with the help of digital schlieren technique. |
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