Margination and segregation in confined flows of blood and other multicomponent suspensions

Blood and many other multicomponent suspensions display a segregation behavior in which different components of the suspension are differentially distributed in the cross-stream direction during flow in a confined geometry such as an arteriole or a microfluidic device. Specifically, in blood the platelets and leukocytes are strongly segregated to the near-wall region and are said to be "marginated". The present work reviews segregation phenomena in multicomponent suspensions. Well-established results on migration and shear-induced diffusion in single-component suspensions are followed by results on binary suspensions of rigid spheres. Then the primary experimental and computational observations are presented for blood and related systems. The final part of the review presents an overview of modeling approaches that attempt to incorporate the physical mechanisms underlying transport phenomena in suspensions into mathematical models - the limited degree of success attained by these models for multicomponent systems is described. The flow-induced segregation in confined mixtures of particles is reviewed, focusing on blood. Detailed summaries of both observations and mechanistic modeling approaches are presented.