Spectral kinetic energy transfer in turbulent premixed reacting flows.
Spectral kinetic energy transfer by advective processes in turbulent premixed reacting flows is examined using data from a direct numerical simulation of a statistically planar turbulent premixed flame. Two-dimensional turbulence kinetic-energy spectra conditioned on the planar-averaged reactant mass fraction are computed through the flame brush and variations in the spectra are connected to terms in the spectral kinetic energy transport equation. Conditional kinetic energy spectra show that turbulent small-scale motions are suppressed in the burnt combustion products, while the energy content of the mean flow increases. An analysis of spectral kinetic energy transfer further indicates that, contrary to the net down-scale transfer of energy found in the unburnt reactants, advective processes transfer energy from small to large scales in the flame brush close to the products. Triadic interactions calculated through the flame brush show that this net up-scale transfer of energy occurs primarily at spatial scales near the laminar flame thermal width. The present results thus indicate that advective processes in premixed reacting flows contribute to energy backscatter near the scale of the flame.
Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA.
C A Z
CA
Towery
Laboratories for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, D.C. 20375, USA.
A Y
AY
Poludnenko
Center for Turbulence Research, Stanford University, Stanford, California 94305, USA.
J
J
Urzay
Center for Turbulence Research, Stanford University, Stanford, California 94305, USA.
J
J
O'Brien
Center for Turbulence Research, Stanford University, Stanford, California 94305, USA.
M
M
Ihme
Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA.
P E
PE
Hamlington