The diverse nature of small-scale turbulence

TL;DR

This paper investigates the nature of small-scale turbulence at high Reynolds numbers, demonstrating that eddies' population densities are scale-invariant, which supports the scenario of diverse small-scale turbulence.

Contribution

It provides empirical evidence that eddies' population densities are scale-invariant in three-dimensional isotropic turbulence, clarifying the nature of small-scale turbulence.

Findings

Eddies' population densities are scale-invariant across the inertial range.

Supports the scenario of small-scale turbulence diversity.

Provides measurements in three-dimensional isotropic turbulence.

Abstract

The self-similar Richardson cascade admits two logically possible scenarios of small-scale turbulence at high Reynolds numbers. In the first scenario, eddies' population densities vary as a function of eddies' scales. As a result, one or a few eddy types dominate at small scales, and small-scale turbulence lacks diversity. In the second scenario, eddies' population densities are scale-invariant across the inertial range, resulting in small-scale diversity. That is, there are as many types of eddies at the small scales as at the large scales. In this letter, we measure eddies' population densities in three-dimensional isotropic turbulence and determine the nature of small-scale turbulence. The result shows that eddies' population densities are scale-invariant.