Persistent cyclonic structures in self-similar turbulent flows

TL;DR

This paper investigates how rotation and helicity influence turbulence, revealing persistent cyclonic vortices and self-similar small-scale behavior, which enhances understanding of geophysical and astrophysical flows.

Contribution

It uncovers the coexistence of long-lived cyclonic vortices with turbulence and identifies self-similarity at small scales in rotating helical turbulence.

Findings

Long-lived laminar cyclonic vortices observed

Small scales exhibit complete self-similarity

No deviations from Gaussianity at small scales

Abstract

Invariance properties of a physical system govern its behavior: energy conservation in turbulence drives a wide distribution of energy among modes, as observed in geophysics, astrophysics and engineering. In hydrodynamic turbulence, the role of helicity (which measures departures from mirror symmetry) remains unclear since it does not alter this distribution. However, the interplay of rotation and helicity leads to significant differences. Using numerical simulations we show the occurence of long-lived laminar cyclonic vortices together with turbulent vortices, reminiscent of recent tornado observations. Furthermore, the small scales are completely self-similar with no deviations from Gaussianity. This result points to the discovery of a small parameter in rotating helical turbulence.