Hindered settling velocity and microstructure in suspensions of solid spheres with moderate Reynolds numbers
Hindered settling velocity and microstructure in suspensions of solid spheres with moderate Reynolds numbers
复制标题
DOI：
10.1063/1.2764109
复制
发表时间：
2007-09
影响因子：
4.6
通讯作者：
Xiaolong Yin;D. Koch
中科院分区：
文献类型：
--
作者：
Xiaolong Yin;D. Koch
格子玻尔兹曼模拟，以确定平均沉降速度和对分布函数的球体沉降在液体中。基于终端速度的雷诺数范围为1至20，固体与流体的密度比为ρp scin ρf=2.0，固体体积分数范围为0.005至0.40。在大于约0.05的体积分数下，平均沉降速度与终端速度u* 的比率可通过幂律表达式u*=k（1-n）n拟合，其中k和n是基于终端速度的雷诺数的函数。常数k通常约为0.86-0.92，u* 偏离稀悬浮液中的幂律行为。这种偏离的程度随着雷诺数的增加而增加。我们发现，受阻沉降速度遵循幂律时，颗粒的微观结构是类似的硬球悬浮液。从幂律行为的偏差可以与各向异性的微观结构所产生的尾流相互作用。
Lattice-Boltzmann simulations are employed to determine the mean settling velocity and pair distribution function for spheres settling in a liquid. The Reynolds number based on the terminal velocity ranges from 1 to 20, the solid-to-fluid density ratio is ρp∕ρf=2.0, and the solid volume fraction is varied from 0.005 to 0.40. At volume fractions larger than about 0.05, the ratio of the mean settling velocity to the terminal velocity u* can be fit by a power-law expression u*=k(1−ϕ)n, where k and n are functions of the Reynolds number based on the terminal velocity. The constant k is typically about 0.86–0.92 and u* deviates from the power-law behavior in dilute suspensions. The extent of this deviation increases with increasing Reynolds number. We show that the hindered settling velocity follows a power law when the particle microstructure is similar to that in a hard-sphere suspension. The deviation from the power-law behavior can be correlated with an anisotropic microstructure resulting from wake intera...