基于格子波尔兹曼气固两相流模型的清洁纤维捕集颗粒过程模拟

Simulation of Particle Capture Process by Clean Fibers Based on Lattice-Boltzmann Method for Gas-Solid Two-Phase Flows

格子波尔兹曼(Lattice-Boltzmenn,LB)格子气(Latticegas automata,LGA)气固两相流模型基于同一套格子描述流体微团与离散颗粒的运动特征,具有可捕获离散相的脉动行为、便于处理复杂和动态边界条件等优点。但现有LB两相流模型尚只能定性描述颗粒行为特征,该文通过求解颗粒在曳力、布朗力等作用下的速度和位移,建立颗粒在格子点间迁移概率的理论模型,定量描述两相流的细节特征。利用此LB两相流模型对圆柱清洁纤维在单个机制(布朗扩散、拦截或惯性碰撞)主导下的捕集颗粒过程进行数值模拟,研究不同纤维体积分数下系统压降变化、及不同机制主导下颗粒捕集经历和总体捕集效率,模拟结果与现有理论或经验公式定量吻合,可为深入理解纤维捕集颗粒的内部特征、发展更合理的颗粒捕集模型等提供依据。

Lattice Boltzmann （LB）Lattice gas automata （LGA） method for gassolid twophase flows is capable of describing the motion of fluid and dispersed particles within the same regular lattices. The LBLGA method is with advantages of being able to capture the fluctuation characteristics of dispersed particles, facilitating the processing of complex and dynamic boundary condition. However, the available LB twophase models just describe the behavior of particles on the qualitative level. The velocity and displacement of particles under drag force and Brownian force were solved explicitly, and the motion probability of a particle to neighboring nodes was accurately modeled, in such a way that the LB two-phase model is capable of simulating two-phase fields on the quantitative level. The resultant LB two-phase model was used to simulate particle capture process by clean fibers by various dominated mechanism （Brownian diffusion, interception and inertial collision）, In addition, the relationship between pressure drop of system and volume of fiber, particle trajectory and capture efficiency by various dominated mechanism were also investigated. It is found that the simulation results agree well with these of available theories or empirical models. It is believed that the LB twophase model can provide evidence for understanding internal feaatre of particle capture process and developing more reasonable capture model.