Helicity cascades in rotating turbulence

TL;DR

This paper investigates how helicity influences energy and helicity cascades in rotating turbulence through high-resolution simulations, revealing that helicity can dominate small-scale dynamics at low Rossby numbers.

Contribution

It demonstrates the significant role of net helicity in rotating turbulence and introduces new inertial indices for energy and helicity spectra based on a phenomenological model.

Findings

Energy cascades to large scales at low Rossby numbers.

Helicity can dominate small-scale cascades in rotating turbulence.

New inertial indices for spectra are predicted.

Abstract

The effect of helicity (velocity-vorticity correlations) is studied in direct numerical simulations of rotating turbulence down to Rossby numbers of 0.02. The results suggest that the presence of net helicity plays an important role in the dynamics of the flow. In particular, at small Rossby number, the energy cascades to large scales, as expected, but helicity then can dominate the cascade to small scales. A phenomenological interpretation in terms of a direct cascade of helicity slowed down by wave-eddy interactions leads to the prediction of new inertial indices for the small-scale energy and helicity spectra.