Serra T, Colomer J, Casamitjana X
Geophysical Fluid Dynamics Laboratory, University of Girona, Girona, 17071, Spain
J Colloid Interface Sci. 1997 Mar 15;187(2):466-73. doi: 10.1006/jcis.1996.4710.
An experimental study was carried out to investigate aggregation and breakup of particles in a Couette flow system with the inner cylinder rotating at constant speed. Experiments were conducted with monodisperse and polydisperse suspensions at different particle volume concentrations. Depending on both the shear stress and the particle concentration, three different regimes were found. In the first regime, when the concentration is less than a critical value, the final diameter of the aggregate is independent of concentration and depends only on the shear. When the concentration is higher, two new regimes are identified, with the final diameter of the aggregate depending on both shear stress and particle concentration. Also, the transition between these two regimes corresponds to the transition from laminar to turbulent flow. In addition, the final diameter of the aggregates in the turbulent flow regime is independent of the size of the primary particles and results to be is controlled by the Kolmogorov length scale. On the contrary, in the laminar flow regime the final diameter of the aggregates shows a light tendency to decrease as the diameter of the primary particles increases.
进行了一项实验研究，以研究在内筒以恒定速度旋转的库埃特流系统中颗粒的聚集和破碎情况。实验针对不同颗粒体积浓度的单分散和多分散悬浮液进行。根据剪切应力和颗粒浓度，发现了三种不同的状态。在第一种状态下，当浓度低于临界值时，聚集体的最终直径与浓度无关，仅取决于剪切力。当浓度较高时，确定了两种新状态，聚集体的最终直径取决于剪切应力和颗粒浓度。此外，这两种状态之间的转变对应于从层流到湍流的转变。另外，湍流状态下聚集体的最终直径与初级颗粒的尺寸无关，结果表明它由柯尔莫哥洛夫长度尺度控制。相反，在层流状态下，随着初级颗粒直径的增加，聚集体的最终直径呈现出轻微的减小趋势。
