B206 格子ガスオートマトン法による反応流れの模擬(LBM・LGAによる流体解析)

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概要

• 論文の詳細を見る

• Since computer performance has drastically increased, numerical simulation is a powerful means for simulation of reactive flow. However, turbulent combustion is still challenging and it is difficult to simulate it with both turbulence and detailed chemistry, because it takes much time to solve 2D or 3D governing equations such as conservation equations of mass and momentum. Recently, Lattice Gas Automata (LGA) has been proposed as an alternative approach for simulating fluids. It describes the fluid at more microscopic level by assuming that it is composed by mesoscopic particles. The hexagonal lattice is used with particles residing on the node, which is shown in Fig.1. The space and time are all discrete, and the physical quantities take only a finite set of values. A set of Boolean variables is introduced to describe the particle occupation. This value is set to be 1 if the cell contains a particle with specified direction, and to be 0 otherwise. Each particle has the same mass and velocity of unity. Macroscopic quantities such as density and velocity are determined by the collective behavior of particles. The scheme of this discrete model is simple and easy for parallel computing. So far, this method has been applied in a large range of fluid simulation including problems of diffusion process, wave propagation, and multi-component fluids. However, few researches have been done to simulate the reactive flow. This may be because it is difficult to describe the reaction term by using the Arrhenius-type equations. In this work, to simulate combustion filed by this LGA, we propose the approach to determine the chemical composition and temperature of the mixture with fast-chemistry assumption. It is called the conserved scalar approach. In this case, the instantaneous chemical composition of the mixture at a given spatial location is at chemical equilibrium, since the local mixture can be considered isolated and to have enough time to react. Then, the temperature and concentration are determined by the degree of mixing of fuel and oxidizer, which are described by the mixture fraction, f. The burned plane in the plot of f versus mass fraction of species and temperature is shown in Fig.2. Two particles of fuel and oxidizer are used for simulating diffusion flame, where the fuel and oxidizer are initially separated (non-premixed). We focus on the flame formed in counter flow of fuel and air streams. The flow configuration and coordinate used are shown in Fig.3. Some results including flow, temperature and concentration fields obtained by this model are shown in Figs 4-6. We conclude that combustion field can be simulated by this two-component LGA model.

• 一般社団法人日本機械学会の論文
• 2001-11-14

著者

• 山本 和弘

  豊橋技科大

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