Turbulent clustering of point particles and finite-size particles in isotropic turbulent flows
Turbulent clustering of point particles and finite-size particles in isotropic turbulent flows
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DOI：
10.1021/ie303507d
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发表时间：
2013-08
影响因子：
4.2
通讯作者：
G. Jin;Yun Wang;Jian Zhang;G. He
中科院分区：
文献类型：
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作者：
G. Jin;Yun Wang;Jian Zhang;G. He
湍流中的颗粒聚团现象在快速流化床提升管内的颗粒-流体两相流动中普遍存在。控制集群的水平是非常关键的，以提高反应效率，在这样的流。本文分别考虑了点颗粒和有限尺寸颗粒，数值研究了湍流中的颗粒聚团问题。采用拟谱方法结合粒子跟踪方法模拟了强迫各向同性湍流中的点粒子簇，采用格子Boltzmann方法模拟了衰减各向同性湍流中的有限尺寸粒子。据观察，由重力等力引起的平均漂移速度可以降低点粒子的粒子聚集水平。然而，颗粒的尺寸大于湍流的特征粘性尺度的颗粒的集群是非常弱的，这是与以前的实验结果相一致。实验结果表明，平均漂移速度和颗粒尺寸可以用来控制化学反应器中颗粒的聚集程度。
Particle clustering in turbulent flows is ubiquitous in particle-fluid two-phase flows in the riser of fast fluidized beds. Controlling the level of clustering is very crucial for improving the reactive efficiency in such flows. The present paper is devoted to numerically studying particle clustering in turbulent flows, where both point particles and finite-size particles are taken into account, respectively. A pseudospectral method with the particle tracking method is used to simulate the point particle clustering in the forced isotropic turbulent flows, while the lattice Boltzmann method is used to simulate the finite-size particles in decaying isotropic turbulent flows. It is observed that the mean drift velocity, caused by forces such as gravity, could reduce the level of particle clustering for point particles. However, the particle clustering is very weak for the particles of sizes larger than the characteristic viscous scales of turbulent flows, which is consistent with the previous experimental results. The observations suggest that the mean drift velocity and particle sizes can be used to control the level of particle clustering in chemical reactors.