Large eddy simulation of combustion using linear-eddy subgrid modeling
Many combustion models in computational fluid dynamics (CFD) today describe either premixed or non-premixed mode of combustion, assuming fast chemistry regimes only. There is a great need for new combustion models that are mode (premixed/non-premixed) and regime (fast/non fast chemistry) independent. The linear-eddy model (LEM) of Kerstein used as a subgrid combustion model for large eddy simulation (LES) called LES-LEM is regarded as a truly mode and regime independent combustion model as it models all the physical processes, i.e. large and small scale turbulent advection, molecular diffusion and chemical reactions at their respective length and time scales.
In this dissertation, a new LEM closure for LES-LEM using the reaction-rate approach is proposed in which the LEM provides closure for the chemical source terms in the conservation equations of the sensible enthalpy and species mass. The new LEM closure is tested on a bluff-body premixed flame problem and simulation results are compared with experiments.
Furthermore, a new splicing approach for modeling large-scale advection in LES-LEM is presented. The approach links the subgrid LEM implementation
to a concept of control-volume crossing rate. A dedicated investigation of splicing is done by simulating passive scalar mixing without the complexity of
chemically reacting flow physics.
Lastly, an improved modeling technique called super-grid LES-LEM is proposed to computationally speed-up LES-LEM.
linear eddy model
large eddy simulation
Chalmers, Mekanik och maritima vetenskaper, Förbränning och framdrivningssystem
A strategy for large-scale scalar advection in large eddy simulations that use the linear eddy sub-grid mixing model
International Journal of Numerical Methods for Heat and Fluid Flow,; Vol. 28(2018)p. 2463-2479
Artikel i vetenskaplig tidskrift
Turbulent-combustion closure for the chemical source terms and molecular mixing using the linear-eddy model
53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017,; (2017)
Paper i proceeding
Effect of the turbulence modeling in large-eddy simulations of nonpremixed flames undergoing extinction and reignition
AIAA SciTech Forum - 55th AIAA Aerospace Sciences Meeting,; (2017)
Paper i proceeding
Subgrid reaction-diffusion closure for large eddy simulations using the linear-eddy model
LES-LEM modellering av förbränning under olika förbränningsmetoder
Vetenskapsrådet (VR) (2017-04479), 2018-01-01 -- 2021-12-31.
Strömningsmekanik och akustik
C3SE (Chalmers Centre for Computational Science and Engineering)
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4563
KB-salen, Kemigården 4, Göteborg
Opponent: Associate Professor Kendal Bushe, Department of Mechanical Engineering, The University of British Columbia, Vancouver, Canada