Pattern of flow around a sphere oscillating an neutrally buoyancy horizon in a continuously stratified fluid
The flow pattern produced by a sphere freely sinking to the neutral buoyancy horizon in a continuously stratified liquid is visualized with different schlieren methods. Dispersion of light in the brine produces colouring of conventional schlieren images when cutting diaphragm is at the edge of blade or thread and is used to form "natural rainbow" colour schlieren image. With sensitive schlieren methods a new structural element is distinguished in the flow pattern. That is a narrow jet covered with a high gradient envelope forming in the neighbourhood of the turning points on the trajectory of the oscillating body. Due to the interaction of the body with the emitted internal waves, and also with the wake and secondary jets, the rate of amplitude damping decreases with time.
stratified fluid oscillating body internal waves secondary jets schlieren technique