Steady and unsteady state velocity and concentration profiles are presented for a 40% by volume suspension of polymethyl methacrylate (PMMA) spheres in polyalkylene glycol (PG). The profiles were obtained by using the noninvasive technique of nuclear magnetic resonance imaging (MRI) in three experimental geometries: coaxial rotating cylinders (i.e., for generating wide‐gap Couette flow), coaxial cylinders in which a straight flight rotates with the inner cylinder and spans the annulus between the surfaces, and a single screw extruder. Concentration profiles document the presence of particle migration from high shear to low shear regions in the concentric cylinder apparatus and in the extruder. However, concentration gradients across the gap in the straight‐flight cylinder are not exhibited, indicating the relative importance of mixing in that geometry. Velocity profiles for the pure PG fluid and for suspension flows which remain well‐mixed agree quantitatively with profiles predicted for Newtonian fluids. Deviations from Newtonian behavior that are present as a result of inhomogeneities in the suspension are interpreted in light of the diffusive‐flux model of particle migration. In particular, in the extruder and straight‐flight geometries it is shown that the importance of migration in causing variations in the particle volume fraction can be predicted from time scales describing the relative rates of circulation and migration. The results obtained from this work provide insight into time scales of particle mixing and migration which can be applied to industrial equipment such as scraped‐surface heat exchangers, static mixers, and commercial extruders.