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Magnetohydrodynamic drag on an oscillating sphere

Published online by Cambridge University Press:  28 March 2006

Robin O. Motz
Robin O. Motz
Affiliation:
Plasma Laboratory, Columbia University, New York City Present address: Department of Physics, Stevens Institute of Technology, Hoboken, New Jersey.
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Abstract

The case of a dielectric sphere executing small-amplitude oscillations in an incompressible, conducting fluid with a uniform magnetic field aligned along the axis of oscillation is studied. For the case of large Hartmann and Reynolds numbers, the MHD equations are linearized. Solutions correct to O(Rm) are obtained for the velocity, pressure, current, and electric and magnetic fields in the fluid. The MHD drag on an oscillating dielectric sphere in mercury was experimentally determined in aligned fields to 0·8 Wb/m2. The experimental results agree well with the theory. The theory and experiment were extended to include the régime where the perturbed velocity is not small compared with the velocity present in the absence of a magnetic field. The validity of using the inviscid velocity to compute the current is verified by measuring the angular dependence of the induced electric field.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 24 , Issue 4 , April 1966 , pp. 705 - 720
Copyright
© 1966 Cambridge University Press

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