J. Vanneste and W. R. Young Consider a two-dimensional axisymmetric vortex with circulation Gamma. Suppose that this vortex is isovortically deformed into an elliptical vortex. We show that the reduction in energy is DeltaE=Gamma ln[(q+q)/2]/(4pi), where q is the ratio of the major to the minor axis of any particular elliptica ... [Phys. Fluids 22, 081701 (2010)] published Mon Aug 9, 2010.
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