Corson James, Mulholland George W, Zachariah Michael R
Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, USA.
Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev E. 2017 Jul;96(1-1):013110. doi: 10.1103/PhysRevE.96.013110. Epub 2017 Jul 18.
We apply our extended Kirkwood-Riseman theory to compute the translation, rotation, and coupling friction tensors and the scalar rotational friction coefficient for an aerosol fractal aggregate in the transition flow regime. The method can be used for particles consisting of spheres in contact. Our approach considers only the linear velocity of the primary spheres in a rotating aggregate and ignores rotational and coupling interactions between spheres. We show that this simplified approach is within approximately 40% of the true value for any particle for Knudsen numbers between 0.01 and 100. The method is especially accurate (i.e., within about 5%) near the free-molecule regime, where there is little interaction between the particle and the flow field, and for particles with low fractal dimension (≲2) consisting of many spheres, where the average distance between spheres is large and translational interaction effects dominate. Our results suggest that there is a universal relationship between the rotational friction coefficient and an aggregate Knudsen number, defined as the ratio of continuum to free-molecule rotational friction coefficients.
我们应用扩展的柯克伍德-里斯曼理论来计算过渡流态下气溶胶分形聚集体的平动、转动和耦合摩擦张量以及标量转动摩擦系数。该方法可用于由相互接触的球体组成的颗粒。我们的方法仅考虑旋转聚集体中初级球体的线速度，而忽略球体之间的旋转和耦合相互作用。我们表明，对于克努森数在0.01至100之间的任何颗粒，这种简化方法的结果与真实值相差约40%以内。该方法在自由分子流态附近尤其准确（即误差在约5%以内），此时颗粒与流场之间的相互作用很小；对于由许多球体组成且分形维数较低（≲2）的颗粒也很准确，因为球体之间的平均距离较大且平动相互作用效应占主导。我们的结果表明，转动摩擦系数与聚集体克努森数之间存在普遍关系，聚集体克努森数定义为连续介质转动摩擦系数与自由分子转动摩擦系数之比。
