Abstract
The authors examine the time delays experienced by migratory particles inside nonuniform flow fields using experimental and numerical methods. Particle trajectories are affected by the particle-fluid density ratio and the flow direction, such that particles may precede or trail the fluid. In flow toward an orifice, the time delay suffered by a single particle is a function of the Froude number Fr and the Archimedes number Ar. When multiple particles are transported radially through a porous medium, time delays manifest through localized annular clogging when 0.05 < Ar-1 < 0.15 and Fr < 6. Gradual particle sedimentation occurs when Ar-1 > 1. Applications include filtration and reservoir fluid extraction. (c) 2007 American Institute of Physics.