Non-universal behaviour of helical two-dimensional three-component turbulence

TL;DR

This paper investigates how strong helical forcing in 2D3C turbulence leads to non-universal behaviors, with the out-of-plane component developing complex dynamics and energy transfer mechanisms influenced by the degree of mirror symmetry in the forcing.

Contribution

It reveals that the out-of-plane component in 2D3C flows exhibits non-universal behavior depending on the mirror symmetry of the small-scale forcing, driven by homochiral triads.

Findings

Out-of-plane component develops non-trivial dynamics under strong helical forcing.

Small-scale helicity injection links 2D and out-of-plane components.

Energy transfer in the out-of-plane component is mediated by homochiral triads.

Abstract

The dynamics of two-dimensional three-component (2D3C) flows is relevant to describe the long-time evolution of strongly rotating flows and/or of conducting fluids with a strong mean magnetic field. We show that in the presence of a strong helical forcing, the out-of-plane component ceases to behave as a passive advected quantity and develops a nontrivial dynamics which deeply changes its large-scale properties. We show that a small-scale helicity injection correlates the input on the 2D component with the one on the out-of-plane component. As a result, the third component develops a non-trivial energy transfer. The latter is mediated by homochiral triads, confirming the strong 3D nature of the leading dynamical interactions. In conclusion, we show that the out-of-plane component in a 2D3C flow enjoys strong non-universal properties as a function of the degree of mirror symmetry of the small-scale forcing.