Multiple-relaxation-time lattice Boltzmann kinetic model for combustion
Aiguo Xu1,2,3, Chuandong Lin4, Guangcai Zhang1,3,5
1National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-26, Beijing 100088, People's Republic of China.
Summary
A new lattice Boltzmann kinetic model (LBKM) probes combustion nonequilibrium. It reveals viscosity and heat conductivity impact thermodynamic and hydrodynamic responses around detonation waves.
Area of Science:
- Computational fluid dynamics
- Chemical kinetics
- Statistical mechanics
Background:
- Combustion processes involve complex hydrodynamic (HNE) and thermodynamic (TNE) nonequilibrium phenomena.
- Existing models like Navier-Stokes primarily describe conserved quantities, limiting the analysis of nonequilibrium effects.
Purpose of the Study:
- To present a two-dimensional multiple-relaxation-time (MRT) lattice Boltzmann kinetic model (LBKM) for simulating combustion phenomena.
- To investigate both hydrodynamic nonequilibrium (HNE) and thermodynamic nonequilibrium (TNE) during combustion.
- To analyze the interplay between HNE and TNE, particularly around detonation waves.
Main Methods:
- Development of a 2D MRT-LBKM incorporating a chemical term to represent released chemical energy.
- The model allows flexible specific-heat ratio and Prandtl number, naturally including TNE effects.
- Verification and validation using benchmark tests, followed by application to 1D detonation processes.
Main Results:
- The MRT-LBKM successfully simulates subsonic and supersonic flows with or without reactions.
- Analysis of detonation waves shows system viscosity/heat conductivity decreases local TNE but increases global TNE.
- Locally, viscosity/heat conductivity exhibits competing trends on TNE due to their involvement in thermodynamic and hydrodynamic responses.
Conclusions:
- The developed MRT-LBKM provides a robust framework for studying complex nonequilibrium phenomena in combustion.
- System viscosity and heat conductivity play a dual role in influencing TNE around detonation waves.
- Understanding these competing effects is crucial for accurate combustion modeling and prediction.
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