Abstract
Cellular deformability may lead to lateral migration of cells toward the centerline during their perfusion in a microfluidic flow chamber. This property can be used for separation of cells of different deformabilities, such as, for example, red and white blood cells. Here, we study the effect of bulk viscoelasticity on lateral migration of cells and particles in shear flow using custom computational fluid dynamics code. The cells and particles are modeled as multiphase (a nucleus surrounded by a layer of cytoplasm) and single-phase viscoelastic drops, respectively. The numerical algorithm is based on the volume-of-fluid continuous-surface-force (VOF-CSF) method and the semi-implicit solvers for the Navier-Stokes equations and the Giesekus constitutive equation for bulk viscoelasticity. Our simulations show the cell/particle with larger deformability moves at a lower translational velocity than the fluid flow. At the same time, it migrates with a relatively constant velocity toward the channel centerline until reaching the equilibrium position. A more deformable cell is characterized by a higher lateral migration velocity, especially when its cytoplasmic viscosity drops to the value of less than 10 P.