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Title: Large-scale anisotropy in stably stratified rotating flows

We present results from direct numerical simulations of the Boussinesq equations in the presence of rotation and/or stratification, both in the vertical direction. The runs are forced isotropically and randomly at small scales and have spatial resolutions of up to $1024^3$ grid points and Reynolds numbers of $$\approx 1000$$. We first show that solutions with negative energy flux and inverse cascades develop in rotating turbulence, whether or not stratification is present. However, the purely stratified case is characterized instead by an early-time, highly anisotropic transfer to large scales with almost zero net isotropic energy flux. This is consistent with previous studies that observed the development of vertically sheared horizontal winds, although only at substantially later times. However, and unlike previous works, when sufficient scale separation is allowed between the forcing scale and the domain size, the total energy displays a perpendicular (horizontal) spectrum with power law behavior compatible with $$\sim k_\perp^{-5/3}$$, including in the absence of rotation. In this latter purely stratified case, such a spectrum is the result of a direct cascade of the energy contained in the large-scale horizontal wind, as is evidenced by a strong positive flux of energy in the parallel direction at all scales including the largest resolved scales.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. National Center for Atmospheric Research, Boulder, CO (United States); Inst. for Chemical-Physical Processes, Rende (Italy); Univ. of California, Berkeley, CA (United States). Space Sciences Lab.
  2. Univ. of Buenos Aires (Argentina)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences,
  4. Univ. of Colorado, Boulder, CO (United States). Laboratory for Atmospheric and Space Physics
Publication Date:
OSTI Identifier:
1159997
Grant/Contract Number:
AC05-00OR22725; 20020110200359
Type:
Accepted Manuscript
Journal Name:
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)
Additional Journal Information:
Journal Name: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print); Journal Volume: 90; Journal Issue: 2; Journal ID: ISSN 1539-3755
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY