Forcing-dependent dynamics and emergence of helicity in rotating turbulence

TL;DR

This study investigates how different types of mechanical forcing influence the behavior of rotating turbulent flows, revealing that forcing characteristics can induce helicity and significantly alter cascade dynamics and flow anisotropy.

Contribution

It demonstrates that the nature of mechanical forcing in rotating turbulence determines flow helicity and cascade behavior, highlighting the role of forcing in flow dynamics and structure formation.

Findings

Forcing with persistent direction induces helicity in rotating turbulence.

Flow anisotropy and energy spectra depend on the forcing mechanism.

Helicity emergence affects cascade dynamics and large-scale energy condensation.

Abstract

The effects of large scale mechanical forcing on the dynamics of rotating turbulent flows are studied by means of numerical simulations, varying systematically the nature of the mechanical force in time. We demonstrate that the statistically stationary solutions of these flows depend on the nature of the forcing mechanism. Rapidly enough rotating flows with a forcing that has a persistent direction relatively to the axis of rotation bifurcate from a non-helical state to a helical state despite the fact that the forcing is non-helical. We find that the nature of the mechanical force in time and the emergence of helicity have direct implications on the cascade dynamics of these flows, determining the anisotropy in the flow, the energy condensation at large scales and the power-law energy spectra that are consistent with previous findings and phenomenologies under strong and weak-wave turbulent conditions.