“Experimental investigation of stratified turbulence: weak turbulence and beyond”

Nicolas Mordant (Université de Grenoble Alpes) will present at the 2022 Simons Collaboration on Wave Turbulence Annual Meeting on December 1st and 2nd in New York.

“Experimental investigation of stratified turbulence: weak turbulence and beyond”:

Wave turbulence of internal waves is a major part of the global ocean dynamics as it contributes to large extent to dissipation of kinetic energy and mixing of temperature and salt by establishing a direct cascade in length scales. Although measurements of turbulence in the ocean interior, the famous Garrett & Munk spectrum, are attributed to internal inertial-gravity wave turbulence, a clear evidence of such turbulence in the laboratory was missing. The large scale Coriolis facility in Grenoble, France is dedicated to geophysical fluid dynamics investigations of stratified and/or rotating flows. It consists in a 13-m diameter pool that can be filled with water with a vertical density gradient (using varying salt concentration) and that can rotate to mimic the action of the rotation of the Earth. We use this facility to obtain a state of stratified turbulence  forced by large scale waves. We report a state of weak wave turbulence of internal waves at intermediate scales. The global flow is more complex as very large scale vortical structures can be observed as well, together with small scale strongly nonlinear turbulence resulting from wave overturning. This complex flow is consistent with the expected phenomenology of such gravity dominated turbulence as observed in the ocean