The effect of hydrodynamic interactions on the orientation of axisymmetric particles flowing through a fixed bed of spheres or fibers
The effect of hydrodynamic interactions on the orientation of axisymmetric particles flowing through a fixed bed of spheres or fibers
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流体动力学相互作用对流经球体或纤维固定床的轴对称颗粒的取向的影响
DOI：
10.1063/1.866809
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发表时间：
1988
影响因子：
4.6
通讯作者：
D. Koch
中科院分区：
文献类型：
--
作者：
E. Shaqfeh;D. Koch
推导了描述流经球体或纤维固定床的轴对称“示踪剂”颗粒稀悬浮液中取向分布演变的平均方程。由于随机分布的固定床颗粒引起的随机波动速度场，自由悬浮的“示踪剂”颗粒的方向发生变化。在小固定床体积分数的限制下，取向分布满足局部取向平流扩散方程，具有有效的旋转扩散率和“漂移”速度，它们是颗粒相对于平均流动方向的取向的函数。该方程的解表明，示踪粒子倾向于以其“薄侧”朝向总体流的方向排列，并且这种排列的程度取决于粒子的纵横比。
Averaged equations describing the evolution of the orientation distribution in a dilute suspension of axisymmetric ‘‘tracer’’ particles flowing through a fixed bed of spheres or fibers are derived. The orientations of the freely suspended ‘‘tracer’’ particles change because of the stochastically fluctuating velocity field induced by the randomly distributed fixed‐bed particles. In the limit of small fixed‐bed volume fraction the orientation distribution satisfies a local orientational advective‐diffusion equation with an effective rotary diffusivity and ‘‘drift’’ velocity, which are functions of the orientation of the particle relative to the direction of the average flow. Solutions of this equation show that the tracer particles tend to align with their ‘‘thin side’’ toward the direction of the bulk flow and that the degree of this alignment depends on the aspect ratio of the particle.