颗粒-流体密度比对两相流动不稳定性影响的格子-Boltzmann方法模拟

采用格子-Boltzmann方法模拟周期性边界计算域内的颗粒流化。计算采用的流化系统Archimedes数为1 432，对应于颗粒终端Reynolds数为30。研究模拟颗粒浓度为25% ，颗粒-流体密度比为2~1 000时，密度比对流体-颗粒流动不稳定性的影响。密度比的范围对应由液固到气固的两相流动。颗粒与颗粒之间的碰撞采用弹性碰撞。研究获得颗粒平均速度、速度方差、偏度及峰度随密度比变化的规律。结合结构因子的分析，因密度比变化使颗粒-流体流动由稳定转变为不稳定的过程中颗粒速度特性变化与聚团形成的关系被确定，也确定了不稳定流动产生时所对应的密度比范围。

Lattice-Boltzmann simulation of the effect of particle-fluid density ratio on instability of two-phase flow

A lattice-Boltzmann method is used to simulate the hydrodynamic property of particles in a periodic domain. An Archimedes number of 1 432 is used for the system corresponding to the terminal Reynolds number of 30. Simulations are carried out when the average solid volume fraction is 25WTB4]%WTBZ], and the density ratio ranges from 2 to 1 000 (from liquid-particle density ratio to gas-particle density ratio). Investigation of the effect of density ratio on stability of the fluid-particle flow system is carried out. The collision among particles is consideved to be elastic. The variations regulations of mean particle velocity, variance, skewness and kurtosis are obtained and analyzed. By combining with the structure factor analysis, the relationships between particle velocity properties and dynamic clusters are determined at different density ratios when the stable-unstable transition occurs, and the density ratio range is also determined.