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On scalings in forced 2D turbulence

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We investigate numerically the validity of Kraichnan-Batchelor scalings for forced 2D turbulence. We use different numerical algorithms and different ways of forcing the flow in order to get results as much independent possible of the conditions of experiments. We systematically observe a deviation from the classical k^-5/3 scaling in the energy inverse cascade inertial range, measuring a steeper slope proportional to k^-2. This steepening is related to the emergence of a population of vortices that dominate the distribution of energy across scales, and whose number density and vorticity distribution with respect to vortex area can be related to the shape of the spectrum.

Author(s):

Jérôme Fontane    
ISAE - Université de Toulouse
France

Richard K. Scott    
School of Mathematics and Statistics, University of St Andrews
United Kingdom

David G. Dritschel    
School of Mathematics and Statistics, University of St Andrews
United Kingdom