Abstract
The paper presents a theoretical model of particle deposition on a single solid sphere in a three dimensional flow field of an incompressible fluid at Reynolds numbers from 200 to 106. The results show collection efficiency fluctuations in time, a factor not previously demonstrated. It is also shown that at low Stokes numbers, the assumptions of axisymmetric and steady flow are particularly poor and therefore, simple two dimensional filtration models used in the literature are not adequate for this case.