Volume 102, Number 4, May 2013
|Number of page(s)||6|
|Section||Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics|
|Published online||12 June 2013|
Inverse cascades in rotating stratified turbulence: Fast growth of large scales
1 National Center for Atmospheric Research - P.O. Box 3000, Boulder, CO 80307, USA
2 Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET - Ciudad Universitaria, 1428 Buenos Aires, Argentina
3 National Center for Computational Sciences, Oak Ridge National Laboratory P.O. Box 2008, Oak Ridge, TN 37831, USA
4 Department of Applied Mathematics, University of Colorado at Boulder - Boulder, CO 80309, USA
Received: 11 March 2013
Accepted: 17 May 2013
We examine the inverse cascade of kinetic energy to large scales in rotating stratified turbulence as occurs in the oceans and in the atmosphere, while varying the relative frequency of gravity to inertial waves, N/f. Using direct numerical simulations with grid resolutions up to 10243 points, we find that the transfer of energy from three-dimensional to two-dimensional modes is most efficient in the range 1/2 ⩽ N/f ⩽ 2, in which resonances disappear. In this range, the cascade is faster than in the purely rotating case, and thus the interplay between rotation and stratification helps creating large-scale structures. The ensuing inverse cascade follows a −5/3 spectral law with an approximately constant flux. This inverse cascade becomes negligible when stratification is dominant.
PACS: 47.55.Hd – Stratified flows / 47.32.Ef – Rotating and swirling flows / 47.27.-i – Turbulent flows
© EPLA, 2013
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