Dissipation scales of kinetic helicities in turbulence

TL;DR

This paper investigates how viscous effects influence the dissipation scales of kinetic helicities in turbulence, revealing that helicity dissipation occurs at the same scale as energy dissipation but requires considering viscous effects at certain wave vectors.

Contribution

It provides a systematic analysis of viscous effects on helicity spectra and fluxes, and estimates the helicity dissipation scale in turbulence.

Findings

Helicity dissipation scale coincides with energy dissipation scale.

Viscous effects are significant for wave vectors below the Kolmogorov scale.

Decomposition into curl eigenmodes reveals viscous effects on helicity evolution.

Abstract

A systematic study of the influence of the viscous effect on both the spectra and the nonlinear fluxes of conserved as well as non conserved quantities in Navier-Stokes turbulence is proposed. This analysis is used to estimate the helicity dissipation scale which is shown to coincide with the energy dissipation scale. However, it is shown using the decomposition of helicity into eigen modes of the curl operator, that viscous effects have to be taken into account for wave vector smaller than the Kolomogorov wave number in the evolution of these eigen components of the helicity.