基于直接力浸入边界法的线形排列多球颗粒沉降特性研究

本文运用直接力浸入边界法对低雷诺数的单个及线形排列的两个和多个球形颗粒自由沉降的特性和过程进行了数值模拟,首先通过单个球形颗粒自由沉降模型验证了该方法的准确性,同时研究了颗粒刚体假设(RBA)对结果精确性的影响,然后,在不同的颗粒间距分布条件下对竖直排列的不同数量的球形颗粒沉降进行了直接数值模拟。模拟结果表明,相对间距在一定范围内的线形排列双球和多球颗粒都可发生相继的牵引、触碰、翻滚过程;当线形排列球颗粒数量大于3时,颗粒的数量不会影响最下方两球初始的牵引和触碰运动;线形排列多球可改变发生牵引的两球的受力从而加速牵引和触碰的过程。

Investigation into sedimentation of linear multi-spheres based on direct forcing immersed boundary method

By means of the direct forcing immersed boundary method (DF-IBM), free sedimentation characteristics and processes of single and linear series of two or more spherical particles were studied in this paper. The method was firstly verified by simulating the sedimentation of a single spherical particle and the effect of rigid body assumption (RBA) on the accuracy of the simulation results was investigated in the meantime. Then, the sedimentation of various numbers of vertically aligned spherical particles in different distances was simulated by direct numerical simulation. The simulation results show that the double-spheres and multi-spheres in linear arrangement will successively experience typical drafting, kissing and tumbling in a certain range of the relative distance between adjacent particles. When the number of spherical particles in linear arrangement is larger than 3, the number of particles will not affect the movement of the lowest two spheres in the initial drafting and kissing. The linear arrangement of multi-spheres can change the force acted on the two spheres in drafting, thus accelerating the process of drafting and kissing.