Athermodynamic Alignment in the Two-Dimensional Enstrophy Cascade

Xin Wang; Shiyi Chen; Robert E. Ecke; Gregory L. Eyink

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Athermodynamic Alignment in the Two-Dimensional Enstrophy Cascade

Xin Wang·Shiyi Chen·Robert E. Ecke·Gregory L. Eyink

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Abstract

We study inertial-range statistics in the direct enstrophy cascade of two-dimensional turbulence via a numerical simulation of the forced Navier-Stokes equation. In particular, we obtain the distribution of the enstrophy flux and of the angle of alignment of the large-scale vorticity gradient with the small-scale vorticity transport vector. These distributions are surprisingly symmetrical and ``athermodynamic'', not explainable by a local eddy-viscosity approximation with coefficient of either positive or negative sign. By a systematic evaluation of the role of various triadic interactions, we can trace the origin of the strong symmetry to the dominance of infrared non-local triads in the enstrophy cascade.

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Xin Wang, Shiyi Chen, Robert E. Ecke, Gregory L. Eyink. 2002-01-22. Athermodynamic Alignment in the Two-Dimensional Enstrophy Cascade. https://arxiv.org/abs/nlin/0201043

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