On Vortex Structure in the Wake of a Sphere.
Technical rept. 1 May 74-30 Apr 75,
CATHOLIC UNIV OF AMERICA WASHINGTON D C HYDRODYNAMICS LAB
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This paper presents results showing the three-dimensional vortex shedding structure when a sphere is towed at a constant velocity through a stratified fluid. It is found that for certain Richardon and Reynolds numbers the vortex is shed three-dimensionally. The stratification however quickly inhibits the vertical motion and the initially turbulent wake collapses and reveals the vertically oriented portion of the vortex structure, reminiscent of two-dimensional vortex street behind a circular cylinder when viewed from above. Two branches of a double helix are continuously unwinding in an opposite sense from the formation region. The double helical model satisfies Thompsons circulation theorem.
- Fluid Mechanics