Excitation of Flow Instabilities due to Nonlinear Scale Invariance

TL;DR

This paper introduces a new kinetic energy source-driven instability mechanism in fluid and plasma flows, utilizing a scale-invariant nonlinear formalism to explain turbulence and irregular motions.

Contribution

It presents a novel approach based on scale invariance to analyze flow instabilities and turbulence in kinetic plasma models, revealing new instability sources and behaviors.

Findings

Langmuir wave dispersion becomes unstable with multifractal measures

Multifractal measures induce non-Gaussian distributions in plasma turbulence

The approach explains anomalous transport in turbulent plasma flows

Abstract

A novel route to instabilities and turbulence in fluid and plasma flows is presented in kinetic Vlasov-Maxwell model. New kind of flow instabilities is shown to arise due to the availability of new kinetic energy sources which are absent in conventional treatments. The present approach is based on a scale invariant nonlinear analytic formalism developed to address irregular motions on a chaotic attractor or in turbulence in a more coherent manner. We have studied two specific applications of this turbulence generating mechanism. The warm plasma Langmuir wave dispersion relation is shown to become unstable in the presence of these multifractal measures. In the second application, these multifractal measures are shown to induce naturally non-Gaussian i.e. a stretched -Gaussian distribution and anomalous transport for tracer particles from the turbulent advection-diffusion transport equation in a Vlasov plasma flow.