Migration in an oscillatory flow of a laminar suspension measured by laser anemometry

Oscillatory flow occurs in a wide range of areas of engineering importance. Two-way lateral migration of particles was observed in the flow of a steady, laminar, dilute, neutrally-buoyant suspension of rigid particles in a tube. The equilibrium particle-position was dependent on the dimensionless Womersley parameter. Experiments were performed in which the Womersley parameter was varied between 1.12 and 8.0. For low values of the parameter, two-way radial migration was observed as in steady, laminar flow. For higher values of the parameter, two equilibrium positions were observed, together with three particle free layers across the radius of the tube.