Rotating helical turbulence. Part I. Global evolution and spectral behavior

TL;DR

This paper investigates how rotation affects the dual cascade of energy and helicity in turbulence, revealing the coexistence of inverse and direct cascades and their impact on flow statistics through high-resolution simulations.

Contribution

It provides new insights into the spectral behavior and cascade dynamics of rotating turbulence with simultaneous energy and helicity injection.

Findings

Inverse energy cascade coexists with direct cascades in rotating turbulence.

Helicity flux dominates over energy flux at low Rossby numbers.

Scaling laws are identified through high-resolution simulations.

Abstract

We present results from two 1536^3 direct numerical simulations of rotating turbulence where both energy and helicity are injected into the flow by an external forcing. The dual cascade of energy and helicity towards smaller scales observed in isotropic and homogeneous turbulence is broken in the presence of rotation, with the development of an inverse cascade of energy now coexisting with direct cascades of energy and helicity. In the direct cascade range, the flux of helicity dominates over that of energy at low Rossby number. These cascades have several consequences for the statistics of the flow. The evolution of global quantities and of the energy and helicity spectra is studied, and comparisons with simulations at different Reynolds and Rossby numbers at lower resolution are done to identify scaling laws.