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Generalised Hele-Shaw flow: A Schwarz function approach

Published online by Cambridge University Press:  16 May 2011

N. R. McDONALD
N. R. McDONALD*
Affiliation:
Department of Mathematics, University College London, WC1E 6BT, UK email: robb@math.ucl.ac.uk
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Abstract

An equation governing the evolution of a Hele-Shaw free boundary flow in the presence of an arbitrary external potential – generalised Hele-Shaw flow – is derived in terms of the Schwarz function g(z, t) of the free boundary. This generalises the well-known equation ∂g/∂t = 2∂w/∂z, where w is the complex potential, which has been successfully employed in constructing many exact solutions in the absence of external potentials. The new equation is used to re-derive some known explicit solutions for equilibrium and time-dependent free boundary flows in the presence of external potentials, including those with singular potential fields, uniform gravity and centrifugal forces. Some new solutions are also constructed that variously describe equilibrium flows with higher order hydrodynamic singularities in the presence of electric point sources and an unsteady solution describing bubbles under the combined influence of strain and centrifugal potential.

Keywords

Hele-Shawfree boundarySchwarz function
Type
Papers
Information
European Journal of Applied Mathematics , Volume 22 , Issue 6 , December 2011 , pp. 517 - 532
Copyright
Copyright © Cambridge University Press 2011

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