A statistical mechanics approach to mixing in stratified fluids
  Predicting how much mixing occurs when a given amount of energy is injected into a Boussinesq fluid is a longstanding problem in stratified turbulence. The huge number of degrees of freedom involved in those processes renders extremely difficult a deterministic approach to the problem. Here we present a statistical mechanics approach yielding prediction for a cumulative, global mixing efficiency as a function of a global Richardson number and the background buoyancy profile. 
Antoine Venaille, Louis Gostiaux, Joel Sommeria
physics.flu-dyn