Shear-driven stratified turbulence at variable Prandtl number

We present a series of direct numerical simulations (DNS) of stratified turbulence, forced by vertical shear, at various Prandtl (Pr=1,7,50) and buoyancy Reynolds (Re_b=30-1000) numbers. Variations in bulk turbulent quantities such as the dissipation rates of kinetic energy and scalar variance are discussed, and are related to changes in local flow structures across the parameter space. Particular attention is given to the influence of increasing Prandtl number, which generates increasingly fine density structures at small scales that in turn strongly influence the bulk mixing statistics. We briefly compare the results of our DNS to experimental measurements of shear-driven turbulence observed in the stratified inclined duct geometry, and discuss potential applications to shear-driven flows occurring in nature.