Self-consistent flows in subsonic interstellar medium fluids

Two-dimensional numerical simulations of a subsonic interstellar medium fluid, characterized by a low turbulent Mach number (M˜<1), demonstrate a self-consistent generation of nonlinear turbulent flows in a hydrodynamic regime. Dynamically weak compressive effects are associated with passively convected thermal fluctuations and these enhance the rate of selective decay. Turbulent relaxation leads to self-organization in thermally dominated velocity fluctuations with the formation of large-scale steady state coherent flows via an inverse cascade mechanism. In agreement with theoretical predictions, thermal and density fluctuations are found to be anti-correlated.