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DNS Study of the Bending Effect Due to Smoothing Mechanism

1
Division of Fluid Mechanics, Lund University, 221 00 Lund, Sweden
2
Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 412 96 Gothenburg, Sweden
*
Author to whom correspondence should be addressed.
Fluids 2019, 4(1), 31; https://doi.org/10.3390/fluids4010031
Received: 28 January 2019 / Revised: 14 February 2019 / Accepted: 15 February 2019 / Published: 19 February 2019
(This article belongs to the Special Issue Numerical Simulations of Turbulent Combustion)
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Abstract

Propagation of either an infinitely thin interface or a reaction wave of a nonzero thickness in forced, constant-density, statistically stationary, homogeneous, isotropic turbulence is simulated by solving unsteady 3D Navier–Stokes equations and either a level set (G) or a reaction-diffusion equation, respectively, with all other things being equal. In the case of the interface, the fully developed bulk consumption velocity normalized using the laminar-wave speed SL depends linearly on the normalized rms velocity u′/SL. In the case of the reaction wave of a nonzero thickness, dependencies of the normalized bulk consumption velocity on u′/SL show bending, with the effect being increased by a ratio of the laminar-wave thickness to the turbulence length scale. The obtained bending effect is controlled by a decrease in the rate of an increase δAF in the reaction-zone-surface area with increasing u′/SL. In its turn, the bending of the δAF(u′/SL)-curves stems from inefficiency of small-scale turbulent eddies in wrinkling the reaction-zone surface, because such small-scale wrinkles characterized by a high local curvature are smoothed out by molecular transport within the reaction wave. View Full-Text
Keywords: reaction waves; turbulent reacting flows; turbulent consumption velocity; bending effect; reaction surface area; molecular transport; direct numerical simulations reaction waves; turbulent reacting flows; turbulent consumption velocity; bending effect; reaction surface area; molecular transport; direct numerical simulations
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Yu, R.; Lipatnikov, A.N. DNS Study of the Bending Effect Due to Smoothing Mechanism. Fluids 2019, 4, 31.

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