Direct numerical simulation of inertia-sensitive turbulence

Abstract

Direct numerical simulations were performed of the turbulent mixing of a contrasted density field by a statistically homogeneous velocity field. The density ratio between the two initially unmixed fluids is 3, thus well beyond the passive-scalar situation. This low Mach number variable density turbulence is relevant to very large Froude-number turbulent mixing processes. In this paper the flow configuration is a forced homogeneous turbulence mixing an initially sharp density-gradient layer. Depending on the characteristic length scales of the velocity and density fields, the order of magnitude of the vortex-stretching and baroclinic enstrophy sources is compared. In the situation where turbulence is inertia affected and where strong baroclinic events are encountered, the deviations from the passive-scalar case are analysed both from the spectral and the statistical points of view.