Stokesian particles on cylinders and spheres

Flow around single cylinders is the elementary model for (he fibrous filter and is the geometry of interest for deposition on pipes, wires, and other such objects in an air flow (Chapter 3). The flow patterns at low and high Reynolds numbers differ significantly, and thi.s affects impaction efficiencies. For Re 100. the velocity distribution outside the velocity boundary layer can be approximated by inviscid flow theory. This approximates the velocity distribution best over the front end of the cylinder which controls the impaction efficiency. The components of the velocity in the direction of the mainstream flow, x, and normal to the main flow, y, are 

The analogous problem of impaction of particles on spheres has been studied for application to gas cleaning In packed beds and aerosol senibbing by droplets. Numerical computations of the impaction efliciency for point particles in in viscid flows around spheres have also been made. Before comparing the numerical computations with the available data, we consider theoretical limiting values for the Stokes number for impaction on cylinders and spheres. 

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