Inertial migration of neutrally buoyant particles in 2D periodic Poiseuille flow with a wide range of particle concentration*

We present a numerical study on the inertial migration of neutrally buoyant particles in 2D periodic Poiseuille flow using a single-relaxation-time lattice Boltzmann method coupled with discrete element method, in which the Hertz contact theory is used to model particle-particle interactions. The channel Reynolds number varies in the range Re=4~100 and the channel-to-particle size ratio is set as 16.67 and 8.33. We examine the effects of particle concentration by increasing the solid fraction from 0 to 50%. The tubular pinch effect (or Segré-Silberberg effect) is observed in our simulations, which agrees quantitatively with the previous experimental and theoretical results. However, as the particle concentration exceeds a certain limit, the particle inertial focusing becomes inconspicuous. As a consequence, a criterion is proposed to distinguish the focusing/non-focusing phenomenon, which depends on the channel Reynolds number, channel-to-particle size ratio, as well as the particle volume fraction.