Singular Measures and Information Capacity of Turbulent Cascades

Michal Shavit, Gregory Falkovich

Research output: Contribution to journalArticlepeer-review

Abstract

How weak is the weak turbulence? Here, we analyze turbulence of weakly interacting waves using the tools of information theory. It offers a unique perspective for comparing thermal equilibrium and turbulence. The mutual information between modes is stationary and small in thermal equilibrium, yet it is shown here to grow with time for weak turbulence in a finite box. We trace this growth to the concentration of probability on the resonance surfaces, which can go all the way to a singular measure. The surprising conclusion is that no matter how small is the nonlinearity and how close to Gaussian is the statistics of any single amplitude, a stationary phase-space measure is far from Gaussian, as manifested by a large relative entropy. This is a rare piece of good news for turbulence modeling: the resolved scales carry significant information about the unresolved scales. The mutual information between large and small scales is the information capacity of turbulent cascade, setting the limit on the representation of subgrid scales in turbulence modeling.

Original languageEnglish
Article number104501
Number of pages5
JournalPhysical review letters
Volume125
Issue number10
DOIs
StatePublished - 31 Aug 2020

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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