Visualizing internal wave generation by finite cylinder oscillations using stereo particle image velocimetry

Abstract

This thesis investigates internal wave generation in a stratified fluid by means of an oscillating cylinder. We observe the consequences of boundary effects by the production of an out-of-plane velocity field as the cylinder span is decreased. Four cylinders are used. Stereoscopic PIV is utilized for flow visualization and velocity field quantification of the three-dimensional internal wave field evolution. This data is analyzed to determine a relationship between the generation source span as a function of out of plane velocity components in the resultant wave field. As the span of the cylinder is systematically decreased, we observe the evolution of the wave field towards three-dimensionality. To better understand the nature of these boundary effects, a horizontal cylinder is imaged at four location along its length. A tilted cylinder is imaged at its end for two forcing frequencies. These experiments allow a qualitative grounding in the production of wave cones from finite cylindrical generation sources.