Dynamics of the decay of an isolated sphere of turbulence

We perform direct numerical simulation and large eddy simulation of an initially spherical region of turbulence evolving in free space. The computations are preformed with a lattice Green’s function method, which allows the exact free-space boundary conditions to be imposed on a compact vortical region. The initial condition is spherically windowed, forced, isotropic turbulence. We study the statistics of the decaying region of turbulence as a function of radius and time. The boundary develops intermittency and features occasional ejections of vortex rings.