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

The energy radiated by a vertically oscillating sphere in a uniformly stratified fluid~has, in shadow-graph 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~\textit{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.