Unstably Stratified Homogeneous Turbulence as a Tool for Turbulent Mixing Modeling

Abstract

In this paper, we propose a kind of buoyancydriven flow leading to unstably stratified homogeneous (USH) turbulence. This approach is developed in the context of incompressible Navier–Stokes equations under Boussinesq approximation. We show that USH turbulence is a valuable tool for understanding and modeling turbulent mixing induced by RayleighTaylor (RT) instability. It is a much simpler configuration than “RT turbulenceâ€‌ which is in fact inhomogeneous. Thus, it gives insights in the basic mechanisms of buoyancydriven turbulence, namely the interplay between buoyancy production, nonlinearities and dissipation. Besides, despite their differences both types of turbulence share very similar features for the large scale characteristics as well as for the inertial range spectrum structure.