Affiliations: Institute for Problems in Mechanics, RAS, prospect
Vernadskogo, 101/1, 119526 Moscow, RUSSIA. e-mail: [email protected]
Abstract: 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.