Effect of surface slip on the relative motion and collision efficiency of slippery spherical particles

The motion of a pair of spherical particles suspended in a viscous fluid is considered under conditions of Stokes flow. The particle surfaces allow the fluid to slip according to the Navier–Maxwell–Basset law. Batchelor and Green׳s mobility functions determining the relative particle motion during interception are computed with high accuracy using a boundary-integral method, and their dependence on the slip coefficient is discussed. The numerical results confirm that particle collision in the presence of surface slip occurs with a finite impact velocity. As the slip coefficient decreases, and thereby the particle surfaces become increasingly slippery, the collision efficiency in uniaxial elongational and simple shear flow increases monotonically from zero for no-slip surfaces to a finite limit for perfectly slippery surfaces.