Hydrodynamic properties of rigid particles: Comparison of different modeling and computational procedures

The hydrodynamic properties of rigid particles are calculated from models c omposed of spherical elements (beads) using theories developed by Kirkwood, Bloomfield, and their coworkers. Bead models have usually been built in su ch a way that the beads fill the volume occupied by the particles. Sometime s the beads are few and of varying sizes (bead models in the strict sense), and other times there are many small beads (filling models). Because hydro dynamic friction takes place at the molecular surface, another possibility is to use shell models, as originally proposed by Bloomfield. In this work, we have developed procedures to build models of the various kinds, and we describe the theory and methods for calculating their hydrodynamic properti es, including approximate methods that may be needed to treat models with a very large number of elements. By combining the various possibilities of m odel building and hydrodynamic calculation, several strategies can be desig ned. We have made a quantitative comparison of the performance of the vario us strategies by applying them to some test cases, for which the properties are known a priori. We provide guidelines and computational tools for bead modeling.