Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation

AMS Citation:
Herbert, C., R. Marino, D. Rosenberg, and A. Pouquet, 2016: Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation. Journal of Fluid Mechanics, 806, 165-204, doi:10.1017/jfm.2016.581.
Date:2016-11-01
Resource Type:article
Title:Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation
Abstract: We study the partition of energy between waves and vortices in stratified turbulence, with or without rotation, for a variety of parameters, focusing on the behaviour of the waves and vortices in the inverse cascade of energy towards the large scales. To this end, we use direct numerical simulations in a cubic box at a Reynolds number Re≈1000Re≈1000, with the ratio between the Brunt–Väisälä frequency NN and the inertial frequency ff varying from 1/41/4 to 20, together with a purely stratified run. The Froude number, measuring the strength of the stratification, varies within the range 0.02 Fr 0.320.02 Fr 0.32. We find that the inverse cascade is dominated by the slow quasi-geostrophic modes. Their energy spectra and fluxes exhibit characteristics of an inverse cascade, even though their energy is not conserved. Surprisingly, the slow vortices still dominate when the ratio N/fN/f increases, also in the stratified case, although less and less so. However, when N/fN/f increases, the inverse cascade of the slow modes becomes weaker and weaker, and it vanishes in the purely stratified case. We discuss how the disappearance of the inverse cascade of energy with increasing N/fN/f can be interpreted in terms of the waves and vortices, and identify the main effects that can explain this transition based on both inviscid invariants arguments and viscous effects due to vertical shear.
Peer Review:Refereed
Copyright Information:Copyright 2016 Cambridge University Press.
OpenSky citable URL: ark:/85065/d7z039s0
Publisher's Version: 10.1017/jfm.2016.581
Author(s):
  • Corentin Herbert - NCAR/UCAR
  • Raffaele Marino
  • Duane Rosenberg
  • Annick Pouquet - NCAR/UCAR
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