A three-dimensional coupled model for particle inertial migration in the presence of micro flows is proposed and implemented. In the present model, the kinetic theory based lattice Boltzmann method is used to describe the fluid flows, and the Newton dynamics equation based model is used to describe the translation and rotation of the particle. The fluid and particle model are coupled by the LBM bounceback scheme based moving boundary method. The processes of particle settlement under gravity and particle rotation in the condition of Couette flow take place. The reliability of the present model and algorithm is validated through comparisons between the present simulation and the benchmark tests in the literature. The simulations of particle migration with various radii in an annular curved channel are performed, and the classic velocity distribution of the secondary flow in the channel cross-section is reproduced successfully. The mechanism of the particle radius influencing the particle equilibrium position in the curved channel is discussed. The results show that the particle equilibrium position in the curved channel will approach to the channel inner wall with the increase of radius. The present model is of important value for detailed study of the particle dynamics in micro flows as well as for the design and development of new micro fluidic particle selective chips and devices.%本文发展了一个能够模拟微流场环境下粒子惯性迁移行为的三维耦合模型.该模型采用基于动理论的格子玻尔兹曼方法(LBM)描述流体流动,采用牛顿动力学模型描述粒子的平动和转动,采用基于LBM反弹格式的运动边界法实现流体与粒子模型的耦合.模拟了重力作用下粒子的沉降过程和Couette流条件下粒子的转动过程,通过将模拟结果与文献中的基准解进行对比定量验证了模型的可靠性.模拟了不同大小的球形粒子在环形流道中的迁移,成功复现了经典的流道截面二次流形成过程,分析了粒径大小对粒子在流道中平衡位置的影响机理.结果表明,粒子在弯流道中的平衡位置与粒径大小密切相关,小半径粒子的平衡位置靠近流道外侧而大半径粒子则靠近流道内侧.通过实验对模拟结果进行了定性验证.本模型为深入研究微流场环境下粒子的运动特性以及开发微流控粒子分选器件提供了参考依据.
展开▼
