A Visual Study on Flow Pattern Around the Strip Moving Uniformly in a Continuously Stratified Fluid

Article type: Research Article

Authors: Chashechkin, Yu.D. | Mitkin, V.V.

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

Abstract: The flow pattern around a thin strip horizontally towed at constant velocity in a continuously stratified liquid is visualized by conventional "Vertical slit-Foucault's knife", "Maksoutov's slit-thread" and "horizontal slit-regular grating" methods. Using these sensitive high-resolution methods enables to reveal new kind of the streaky structure including a sequence of thin sloping interfaces both on the strip surface and inside its wake. When velocity or distance from the strip increases, the streaks may be turned into the sloping or nearly horizontal interfaces. Reconnections of outer edges of the streaks result in appearance of a set of symmetrical "butterfly-like" vortices, which are perturbed by a shear flow inside the downstream wake. Lift forces caused by a slope of the strip produce an asymmetry of the wake and lead to fast degeneration of the streaky structures.

Keywords: Schlieren technique, Stratified fluid, Horizontal strip, Internal waves, Streaky structures

Journal: Journal of Visualization, vol. 7, no. 2, pp. 127-134, 2004