An Immersed Boundary-Lattice Boltzmann Prediction for Particle Hydrodynamic Focusing in Annular Microchannels**Supported by the National Natural Science Foundation of China under Grant Nos 51728601 and 51771118, and the Natural Science Foundation of Jiangsu Province under Grant No BK20150600.

Abstract

We numerically study the dynamics of particle crystals in annular microchannels by the immersed-boundary (IB) lattice Boltzmann (LB) coupled model, analyze the fluid-particle interactions during the migration of particles, and reveal the underlying mechanism of a particle focusing on the presence of fluid flows. The results show that the Reynolds and Dean numbers are key factors influencing the hydrodynamics of particles. The particles migrate onto their equilibrium tracks by adjusting the Reynolds and Dean numbers. Elliptical tracks of particles during hydrodynamic focusing can be predicted by the IB-LB model. Both the small Dean number and the small particle can lead to a small size of the focusing track. This work would possibly facilitate the utilization of annular microchannel flows to obtain microfluidic flowing crystals for advanced applications in biomedicine and materials synthesis.