双柱状颗粒在线性剪切流场中的动力学分析

为研究柱状颗粒在线性剪切流场中的运动状态和受力情况，本文以颗粒长径比为2，颗粒之间的初始距离ΔS_Py=4D为例，基于直接力浸入边界法数值模拟了双柱状颗粒在三维线性剪切流场中的运动过程。根据模拟结果分析了柱状颗粒周围流场参数分布，在考虑壁面对颗粒的影响和颗粒之间相互影响的条件下，研究了颗粒的受力和运动的变化，探索了流体曳力导致柱状颗粒迁移和转动的规律。研究结果表明，双柱状颗粒在线性剪切流场中易向速度大的流体区域运动；前后两颗粒运动状态和轨迹不同，颗粒之间距离较近时，曳力会产生较大的波动；只有当颗粒在壁面附近时，滞后颗粒才能追上领先颗粒，两颗粒发生牵引、翻滚和分离过程。

Dynamic analysis of the double columnar particles in a linear shear flow

Based on the direct forcing immersed boundary method, this paper presents numerical simulations of the movement of the double columnar particles in a three-dimensional linear shear flow to study the movement state and force of columnar particles.The aspect ratios of the double columnar particles are 2, and the initial distance between the particles ΔS_Py is 4D.According to the simulation results, the parameter distribution of the flow around the columnar particles is obtained.The changes in force and movement of the columnar particles as well as the law of the movement and rotation of the particles caused by the fluid drag force are studied, considering the influence of wall on particles and the mutual influence between the two particles.Results show that the double columnar particles tend to move towards the high-speed area in a linear shear flow.The movement and trajectory of the two particles are different.The drag force fluctuations are greater if the distance between the particles is relatively close.The lagging particle can catch up with the leading particle when they move near the wall, and the drafting, tumbling and separating occur.