Dependence of Intermittency on Turbulence Intensity, Fuel Type, and Simulation Fidelity in Premixed Reacting Flows

Abstract

Intermittency is an important metric for determining the likelihood of extreme fluctuating quantities in turbulent premixed flames. Such extreme quantities may lead to flow-altering events including extinction, auto- and re-ignition, and deflagration to detonation transitions. Here we analyze intermittency of enstrophy (i.e., vorticity magnitude) and temperature gradient magnitude fields based on data from direct numerical simulations (DNS) of stoichiometric premixed flames in unconfined domains. The DNS are performed for different turbulence intensities and fuels, for single- and multi-step chemistry models, for varying spatial resolution, and for temperature-dependent and constant viscosities. These simulations thus enable the study of physical effects on intermittency, as well as the study of effects based on simulation fidelity. We show that intermittency in the temperature gradient magnitude varies with the chemistry model but has little dependence on viscosity, while enstrophy intermittency varies with the viscosity model, but has little dependence on the fidelity of the chemistry.

Sam Whitman
Sam Whitman
PhD student
Colin Towery
Colin Towery
Postdoctoral Research Associate

Colin is a former research associate in the Paul M. Rady Department of Mechanical Engineering at the University of Colorado Boulder and also a former student in the Turbulence and Energy Systems Laboratory, earned his PhD in May 2018.

Peter Hamlington
Peter Hamlington
Associate Professor

Peter is an associate professor in the Paul M. Rady Department of Mechanical Engineering at the University of Colorado Boulder and the principal investigator of the Turbulence and Energy Systems Laboratory.