In this paper, the numerical investigation of the bubble formation and rise in gas-liquid-solid flow systems has been done through a coupled numerical method, the so-called volume of fluid (VOF) method, and a discrete element model (DEM). VOF is used to capture the interface of the bubble and DEM is employed to track the movement of particles. This coupled numerical method is validated through the good consistency of our calculated results to those experimental data (from other literature) of a bubble rising in a gas-liquid-solid system. The calculation results in this paper disclose that the detachment time of the first formed bubble is longer for case I (when particles are lying at the bottom of the container) than for case II (when the particles are settling freely). The main reason is that a stronger circulation (induced by the sedimentation of particles) near the bottom of the container plays a stronger cutting role and speeds up the detachment of the bubble. Then, the effects of some factors including particle volume fractions, gas velocities, orifice sizes, surface tensions, and liquid densities on the bubble formation and rise have also been investigated systematically. This work is useful for further research on the gas-liquid-solid fluidized bed system.

中文翻译：

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气固两相流系统中沉降颗粒对气泡形成的影响

本文通过耦合数值方法，所谓的流体体积（VOF）方法和离散元模型（DEM）对气液固流系统中气泡的形成和上升进行了数值研究。 。VOF用于捕获气泡的界面，DEM用于跟踪粒子的运动。这种耦合数值方法通过我们的计算结果与气-液-固系统中气泡上升的实验数据（来自其他文献）的良好一致性而得到验证。本文的计算结果表明，情况I（当颗粒位于容器底部时）的第一个气泡的脱离时间要长于情况II（当颗粒自由沉降时）的分离时间。主要原因是容器底部附近的更强循环（由颗粒的沉淀引起）起着更强的切割作用，并加速了气泡的分离。然后，还系统地研究了一些因素，包括颗粒体积分数，气体速度，孔口尺寸，表面张力和液体密度对气泡形成和上升的影响。这项工作对于进一步研究气-液-固流化床系统很有用。