Lattice Boltzmann study of micro branch array of crossflow filtration for fluid partitioning

In the past decade, a flurry of new blood cells separation methods based microfluidic chip technology has emerged to address clinical diagnosis and biological research. The crossflow-based filtration separation method, because of its simple working principle and effectively overcoming the chip clogging problem, is gradually developing as an attractive solution for blood cells separation. In order to investigate and optimize the structure of a crossflow-based separator for blood cells, we studied how the tilt angle of the micro branch channel in the pillar array affects the fluid partitioning of low Reynolds number using Lattice Boltzmann (LBM) method. The reliability of using LBM to solve the flow of fluid of low Reynolds number is validated by the simulation of Poiseuille flow, and then a model of the branch channel, which mainly focuses on 4 different tilt angle (30°, 45°, 60°, 90°), is built to simulate. For far upstream and downstream in the main channel, and downstream in the side branch array channels, the fluid velocity profiles are assumed to adopt those of unidirectional Poiseuille flow with prescribed flow rates. The results show that the angle of inclination, with other conditions constant, will significantly influence the partition of fluid in the main channel and side branch array channels. Generally the larger the tilt angle is, the larger the rate flow in the branch array channel is, or vice versa.