Analytic derivation of the inertial range of compressible turbulence

TL;DR

This paper develops an analytic model to derive the inertial range power spectrum of compressible turbulence, revealing a -2 power law consistent with astrophysical observations and simulations.

Contribution

It introduces a novel analytic approach to model the inertial range in compressible turbulence, accounting for energy diversion into compression.

Findings

Inertial range follows a -2 power law spectrum.

Model aligns with observed astrophysical turbulence spectra.

Numerical simulations support the derived power spectrum.

Abstract

An analytic model for steady state turbulence is employed to obtain the inertial range power spectrum of compressible turbulence. We assume that for homogeneous turbulence, the timescales controlling the energy injected at a given wavenumber from all smaller wave-numbers, are equal for each spatial component. However, the longitudinal component energy is diverted into compression, so the rate controlling the energy that is transferred to all larger wave-numbers by the turbulent viscosity is reduced. The resulting inertial range is a power law with index -2. Indeed such power spectra were observed in various astrophysical settings and also in numerical simulations.