Examination of Turbulent Kinetic Energy Transfer in Realistic Premixed Reacting Flows | CU Experts

Abstract; We investigate the kinetic energy flux across different spatial scales for a premixed flame in a realistic configuration. We use PeleC, a fully-compressible reacting flow code with adaptive mesh refinement, to obtain a fully-resolved flow field for a bluff body stabilized premixed methane-air flame situated within a converging nozzle and subjected to free-stream turbulence. We apply Gaussian filters of multiple sizes to the simulation data to evaluate the net kinetic energy flux between resolved (i.e., large) and sub-grid (i.e., small) scales, with transfer from small to large scales corresponding to energy “backscatter”. Using three filter sizes, we find that there is statistically-significant amounts of backscatter towards the unburned side of the flame, coinciding with regions of high flame-generated enstrophy production due to baroclinic torque. Despite the same general trends recovered through each of the filters, backscatter is more pronounced for the smaller filter widths that are a fraction of the thermal flame thickness, indicating that backscatter becomes less pronounced further from the flame scale in this flow.

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