Binder Christian, Hartig Martin A J, Peukert Wolfgang
Institute of Particle Technology, University of Erlangen-Nuremberg, Cauerstr. 4, 91058 Erlangen, Germany.
J Colloid Interface Sci. 2009 Mar 1;331(1):243-50. doi: 10.1016/j.jcis.2008.11.021. Epub 2008 Nov 17.
Aggregates settle in viscous fluids in specific directions depending on their morphology. We investigated the settling behavior of fractal aggregates with D(f)=1.85 in fluids using the Accelerated Stokesian Dynamics method. The results have been compared with experimental data. A simple equation is proposed which gives the drag force in dependence on the radius of gyration r(gyr), the projection area A(p) and the aggregate orientation during settling. This equation reproduces the data from ASD within +/-10% for Re <1. Additionally, a new algorithm has been developed which allows a prediction of the orientation of such fractal aggregates provided that they have time enough to orient in the fluid. Moreover, the drag force acting on them can be predicted in a narrow range (maximum error 15%). This algorithm allows a very fast evaluation of the orienting behavior with small deviations.
聚集体在粘性流体中会根据其形态沿特定方向沉降。我们使用加速斯托克斯动力学方法研究了分形维数D(f)=1.85的聚集体在流体中的沉降行为。并将结果与实验数据进行了比较。提出了一个简单的方程，该方程给出了与回转半径r(gyr)、投影面积A(p)以及沉降过程中聚集体取向有关的曳力。对于雷诺数Re<1的情况，该方程对加速斯托克斯动力学数据的再现误差在±10%以内。此外，还开发了一种新算法，只要分形聚集体有足够的时间在流体中取向，就可以预测其取向。而且，作用在它们上的曳力也能在较窄范围内（最大误差15%）进行预测。该算法能够以较小偏差非常快速地评估取向行为。
