Inertial migration of spherical particles in curved microfluidic ducts*

Finite size particles suspended in flow through micro-scale ducts are known to migrate across streamlines and focus towards stable equilibria whose location depends on a variety of factors. This has a several practical applications involving the separation and isolation of cells. I will describe some of our work on modelling inertial migration of spherical particles at low Reynolds numbers in curved ducts having rectangular and trapezoidal cross-sections. Via a careful analysis of the coupled particle fluid motion we have been able to separate the effects of inertial lift and drag due to secondary fluid motion. By computing these forces and subsequently reconstructing particle motion we have been able to demonstrate some clear relationships between the lateral focusing location and three physical length scales. Moreover we have been able to identify a number of interesting dynamical changes that take place over the device design parameter space.