Numerical Simulation of Two-Dimensional Turbulence with High-Symmetry

A two-dimensional high-Reynolds number flow is simulated starting from a high-symmetric random initial condition. At early stages of evolution narrow band regions of vorticity are built-up by stretching of equivorticity lines. They are broken down into a block of eddies of very complicated structure through a rolling-up instability and subsequent stretching and reconnection processes of equi-vorticity lines. Around this break-down time the enstrophy-dissipation rate takes the maximum value and the power form of the energy spectrum in the inertial range changes from k -4.2 to k -3 .