Three dimensional internal-wave radiation by a horizontally oscillating body in a uniformly stratified fluid

Evgeny V. Ermanyuk (1) , Jan-Bert Flór (2) , Bruno Voisin (2)

1 LIH - Lavrentyev Institute of Hydrodynamics
2 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

The energy radiated by a vertically oscillating sphere in a uniformly stratified fluid has, in shadowgraph and schlieren images, the well known "St. Andrew cross" ray pattern. Since the wave length does not appear in the dispersion relation, the spatial structure of internal waves has non-trivial dependence on the body geometry, direction and frequency of oscillations, and the viscosity. In contrast to former investigations, in the present investigation we consider the asymmetric 3D wave pattern for large and small amplitude horizontal oscillation of different size spheres. New experimental techniques are explored. For small oscillations good agreement is found with linear theory; in addition to comparison between experimental data and theoretical (near-field) solution we also present the comparison between the far-field and near-field solutions.

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Evgeny V. Ermanyuk, Jan-Bert Flór, Bruno Voisin. Three dimensional internal-wave radiation by a horizontally oscillating body in a uniformly stratified fluid. 61st Annual Meeting of the APS Division of Fluid Dynamics, Nov 2008, San Antonio, United States. ⟨hal-00583061⟩