Dynamics of particles in liquid-liquid stratified flow in a microchannel

Inertial focusing is a separation technique where particles migrate laterally to equilibrium positions in the presence of finite inertia. These equilibrium positions are predominantly governed by two counteracting forces namely the wall lift force and the shear gradient force. The equilibrium positions can be altered by changing the velocity profile of the fluid. This is done for the separation and recovery of cells from one fluid to the other.

In this work, we model the inertial focusing of particles in the laminar, liquid-liquid stratified flow in a microchannel. The particles are sent through one fluid and due to variation in shear gradient (curvature in velocity profile), the particles migrate towards the other fluid. Towards this, we develop a 2D model (pressure driven flow between infinite parallel plates) based on the immersed boundary method to study the hydrodynamics and particle migration. The effect of fluid and particle properties and the operating conditions such as phase holdup and Reynolds number is analyzed on the particle migration.