Observations of Secondary Flows Generated by a Torsionally Oscillating Sphere in Linearly Stratified Fluids

R.F. Folse

Document Type

Article

Publication Date

2-1-1994

Department

Physics and Astronomy

School

Mathematics and Natural Sciences

Abstract

Observations have been made of a cellular flow pattern in the secondary flow field generated by a sphere, 2.52 cm in radius, torsionally oscillating in linearly stratified fluids (Brunt–Väisälä frequencies, N, between 0.9 and 2.1 rad/s). Shadowgraphs were made of the secondary flow for frequencies of oscillation in the range 2.0 rad/s≤ω≤13.5 rad/s, and amplitudes of oscillation θ≤1 rad. The size and number of flow cells were determined for fixed values of the parameter (ω/N)θ2, and bifurcation‐like transitions occurred during continuous variations of this parameter. Flow cells were mapped using a laser‐Doppler velocimeter and compared to the secondary flow for homogeneous fluids. A phase diagram is presented to show the range of critical values of parameters where flow transitions occur.

Publication Title

Physics of Fluids

Volume

6

Issue

2

First Page

537

Last Page

540

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