Self-organizing effect of drift term against diffusion term in point vortex system evidenced by numerical simulations on PEZY-SC

We have analytically obtained a kinetic equation for a two-dimensional (2D) point vortex system with a Fokker-Planck type collision term consisting of a diffusion term and a drift term (Yatsuyanagi and Hatori 2015 Fluid Dyn. Res. 47 065506). The equation describes a mechanism of a self-organization in the system. In this paper, analytically anticipated characteristics of the collision term is evidenced by numerical simulations on PEZY-SC supercomputer system. In the previous paper, it is shown that the collision term satisfies following physically good properties: (1) charge separated, self-organized distribution typical for negative absolute temperature is achieved by the drift term, (2) when a system reaches a thermal equilibrium state, stream function psi and vorticity omega satisfies an inequality d omega/d psi>0