Numerical investigation of the effect of particle concentration and size on the Dean's flow in a curved microchannel*

Microfluidic devices have been widely employed for the purpose of clinical diagnostic tests, cell sorting, flow cytometry, particle manipulation, etc. Inertial microfluidics has been one of the most extensively used passive particle manipulation techniques, where hydrodynamic forces are used for sorting, or separating particles in a microchannel. Despite its popularity, there is a lacuna in our understanding of the particle-fluid two-phase transport in curved microchannels. In this study, we incorporate a multiphase Eulerian model to study such a two-phase transport in the presence of Dean flow in a curved microchannel. Firstly, we witness a significant shift of the location of maximum velocity away from the channel walls opposing the effect of Dean's flow at large particle concentrations. Secondly, we observe a massive modification of the counter-rotating vortices associated with the Dean's flow. We attribute such alterations in the typical Dean flow characteristics to the interphase interaction forces which oppose the effect of curvature-induced centrifugal force. Such an understanding of interphase interaction forces will be critical in designing better particle/cell focusing devices.