Helical distributed chaos in rotating turbulence and convection (with applications to geomagnetic dynamo)

TL;DR

This paper investigates helical distributed chaos in rotating turbulence and convection, highlighting the significance of helicity moments, with applications to geophysical phenomena like the geomagnetic dynamo.

Contribution

It introduces the concept of helical distributed chaos and demonstrates its relevance in rotating turbulence and convection, supported by simulations, experiments, and observations.

Findings

Even with zero global helicity, local regions exhibit non-zero even moments.

Helicity moments act as adiabatic invariants in rotating turbulence.

Applications to stellar convection zones and geomagnetic dynamo are discussed.

Abstract

The role of the moments of helicity distribution in rotating turbulence has been studied using the notion of helical distributed chaos. Results of the direct numerical simulations, laboratory experiments and geophysical observations have been used in this investigation. It is shown, in particular, that even for the cases when the global helicity is equal to zero at least even moments are usually non-zero (due to the appearance of the local spatial regions with strong negative and positive helicity) and can play a significant role in the rotating turbulence as adiabatic invariants. Rotating buoyancy driven thermal convection (Rayleigh-B\'{e}nard and Rayleigh-Taylor, the former also for the magnetohydrodynamics) is also studied, and applications of this approach to the convection zone of massive stars and to the geomagnetic dynamo have been discussed in this context.