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Generation of internal waves plays essential role in dynamics of a body motion in a stratified fluid. In particular, internal-wave radiation by oscillating bodies in a uniformly stratified fluid represent a well-known generic problem aimed on the understanding of relation between the geometry of the oscillating body, fluid viscosity, and the role of transient effects in the formation of internal-wave beams. In the present report we re-visit this problem. As the main experimental tool for quantitative measurement of internal-wave parameters we use a version of syntetic schieren technique (Sutherland et al, JFM, 1999, V. 390). The fields of internal waves generated by cylinders with circular, square and diamond-shaped cross sections are measured for a range of non-dimensional oscillation frequencies and Stokes numbers. Particular attention is paid to the variation of the shape of internal-wave envelopes with distance for generators of different shapes and sizes, and transient effects due to start-up of harmonic oscillations of the cylinders in the otherwise quiescent fluid. The study outlined in this poster represent a part of research program of my PhD thesis executed under the guidance of Prof. E.V. Ermanyuk at Lavrentyev Institute of Hydrodynamics. |
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