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Slow viscous flow past a rotating sphere

Published online by Cambridge University Press:  24 October 2008

K. B. Ranger
Affiliation:
University of Toronto, Toronto, 181, Canada

Extract

Keller and Rubinow(l) have considered the force on a spinning sphere which is moving through an incompressible viscous fluid by employing the method of matched asymptotic expansions to describe the asymmetric flow. Childress(2) has investigated the motion of a sphere moving through a rotating fluid and calculated a correction to the drag coefficient. Brenner(3) has also obtained some general results for the drag and couple on an obstacle which is moving through the fluid. The present paper is concerned with a similar problem, namely the axially symmetric flow past a rotating sphere due to a uniform stream of infinity. It is shown that leading terms for the flow consist of a linear superposition of a primary Stokes flow past a non-rotating sphere together with an antisymmetric secondary flow in the azimuthal plane induced by the spinning sphere. For a3n2 > 6Uv, where n is the angular velocity of the sphere, U the speed of the uniform stream, and a the radius of the sphere, there is in the azimuthal plane a region of reversed flow attached to the rear portion of the sphere. The structure of the vortex is described and is shown to be confined to the rear portion of the sphere. A similar phenomenon occurs for a sphere rotating about an axis oblique to the direction of the uniform stream but the analysis will be given in a separate paper.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1971

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References

REFERENCES

(1)Rubinow, S. I. and Keller, J. B.The transverse force on a spinning sphere moving in a viscous fluid. J. Fluid Mech. 11 (1961), 447459.CrossRefGoogle Scholar
(2)Childress, S.The slow motion of a sphere in a rotating viscous fluid. J. Fluid Mech. 20 (1964), 305.CrossRefGoogle Scholar
(3)Brenner, H.Effect of finite boundaries on the Stokes resistance of an arbitrary particle. J. Fluid Mech. 12 (1962), 35.CrossRefGoogle Scholar