BOUNDARY-ELEMENT METHOD CALCULATIONS OF THE MOBILITY OF NONSPHERICAL PARTICLES .1. LINEAR-CHAINS

The utility of the boundary element technique is demonstrated on the p roblem of linear chains of spheres translating and rotating through a quiescent fluid. The method takes advantage of the linearity of the pr oblem by using superposition of the general solution for the flow gene rated by point forces on the bounding surfaces of the fluid to satisfy the boundary conditions. The HEM results for translational drag of ch ains of spheres compare very well with published experimental and comp utational data. We also show that slender body theory provides an appr oximate analytic result that is useful in interpreting and correlating the BEM calculations. Slender body theory also revealed that the mode l of the particle as a single prolate spheroid with equal aspect ratio produced a result equal to that for the chain of spheroids correct to second order, while the model of the chain as a cylinder produced an upper bound on the drag. Slender body theory also gives a reasonable e stimate for the rotational resistance for chains, which, together with the BEM results, are reported here for the first time.