ON THE EVOLUTION EQUATION OF AN INVISCID VORTEX IN 2-D TURBULENCE

Using a stochastic method, an evolution equation for an inviscid 2-D vortex is derived to calculate probability distributions of its position r over arrow pointing right (t), vorticity amplitude omega and size l. For a vortex in an external rotating strain, a critical curve found divides the existence and non-existence of the vortex in the parameter space. This curve is in agreement with known results for a steady elliptical vortex in strain, except in a region where the vorticity of the vortex is opposite to that of the external flow, the vortex is not predicted to survive statistical fluctuations.