The three-dimensional state of stratified shear instability in cold water

Stratified shear instability is one of the most widely studied routes to turbulence that occurs in natural waters. We report on simulations in the cold water regime relevant to late winter/early spring lakes, which is characterized by very small density differences and a nonlinear equation of state. The stratified shear instability in this regime achieves a three-dimensional state but it is not a priori clear that a substantial inertial subrange exists. We quantify the manner in which the three-dimensional state dissipates momentum and mixes scalars, and report on the nature of coherent structures in the flow with a focus on late times.