Odd viscosity suppresses intermittency in direct turbulent cascades

TL;DR

This paper demonstrates that odd viscosity, a non-dissipative property in parity-breaking fluids, suppresses intermittency in turbulent flows by inducing parity-breaking waves, leading to more self-similar turbulence at small scales.

Contribution

It introduces a novel understanding of how odd viscosity affects turbulence, supported by simulations and a new shell model that captures the suppression of intermittency.

Findings

Odd viscosity suppresses small-scale intermittency in turbulence.

Parity-breaking waves induced by odd viscosity break scale invariance.

A two-channel helical shell model reproduces turbulence suppression phenomena.

Abstract

Intermittency refers to the broken self-similarity of turbulent flows caused by anomalous spatio-temporal fluctuations. In this Letter, we ask how intermittency is affected by a non-dissipative viscosity, known as odd viscosity (also Hall or gyro-viscosity), which appears in parity-breaking fluids such as magnetized polyatomic gases, electron fluids under magnetic field and spinning colloids or grains. Using a combination of Navier-Stokes simulations and theory, we show that intermittency is suppressed by odd viscosity at small scales. This effect is caused by parity-breaking waves, induced by odd viscosity, that break the multiple scale invariances of the Navier-Stokes equations. Building on this insight, we construct a two-channel helical shell model that reproduces the basic phenomenology of turbulent odd-viscous fluids including the suppression of anomalous scaling. Our findings illustrate how a fully developed direct cascade that is entirely self-similar can emerge below a tunable length scale, paving the way for designing turbulent flows with adjustable levels of intermittency.