Experimental observation of a strong mean flow induced by internal   gravity waves
  We report the experimental observation of a robust horizontal mean flow induced by internal gravity waves. A wave beam is forced at the lateral boundary of a tank filled with a linearly stratified fluid initially at rest. After a transient regime, a strong jet appears in the wave beam, with horizontal recirculations outside the wave beam. We present a simple physical mechanism predicting the growth rate of the mean flow and its initial spatial structure. We find good agreement with experimental results. 
Guilhem Bordes (Phys-ENS), Antoine Venaille (Phys-ENS), Sylvain   Joubaud (Phys-ENS), Philippe Odier (Phys-ENS), Thierry Dau...
physics.flu-dyn physics.ao-ph