M. Stastna  and D. Deepwell,  Shear-instability in Internal Kelvin waves

Internal waves in the ocean and their laboratory analogues are known to break down via a variety of mechanisms.  
In this talk I will focus on Direct Numerical Simulations of mode-2 internal waves generated from a lock-release 
on a laboratory scale.  This well-understood process of generation allows us to control the size and shape of 
the wave formed, for example through a judicious choice of density stratification.  In the absence of rotation 
the internal waves generated, primarily induces stream wise and vertical currents, with span wise currents being 
the product of small scale three-dimensionalization. When rotation is present, the process of geostrophic adjustment 
leads to a complex pattern of wave-induced currents oriented in all three coordinate directions.  I will demonstrate 
that this leads to shear instabilities that are trapped near one of the tank walls, it also leads to smaller scale 
shear instabilities with a stream wise oriented vorticity axis (to our knowledge the first documented case of 
such instabilities).  I will discuss the breakdown into turbulence of these instabilities and the possibilities and 
challenges of scale up of these simulations to the field scale.