Numerical evaluation of lift forces acting on a solid particle in a microchannel

Abstract

Lift forces acting on a single particle are numerically investigated when it is flowing in a square microchannel. Specifically, effects of particle size and rotation on the lift forces are examined by numerical simulation. To this end, a Lagrangian particle tracking method is developed that couples the discrete element method with the direct numerical simulation for precise evaluation of the particle-fluid interaction. Thermal fluctuations are also considered in the method. We find that the equilibrium positions of the focused particle shift toward the channel axis as the particle size increases. The thermal fluctuations can affect the lift forces especially at lower Reynolds number. It is also shown that particle rotation considerably affects the lift forces as opposed to previous interpretation of the contribution of rotation to the lift forces.