Mixing in modulated turbulence. Numerical results

TL;DR

This paper uses direct numerical simulations to study how periodic forcing affects scalar mixing in isotropic turbulence, revealing that high-amplitude modulation at low frequencies reduces mixing efficiency and alters characteristic timescales.

Contribution

It provides new insights into the frequency-dependent response of scalar mixing rates and timescales under modulated turbulent conditions.

Findings

High modulation amplitudes decrease average mixing rates at low frequencies.

Mixing timescales increase with high-amplitude modulation.

Velocity timescales decrease under strong periodic forcing.

Abstract

Direct numerical simulations are carried out to investigate scalar mixing in an isotropic turbulent flow with a time-periodic forcing. For high amplitudes of the modulation, it is shown that the average mixing rate is negatively affected at low frequencies. In this limit the mixing time scale increases, whereas the typical velocity timescale decreases. We further determine the frequency response of scalar statistics to a periodic scalar-forcing.