YAO Tong-lin, YU Zhao-sheng, SHAO Xue-ming

(Department of Mechanics, Zhejiang University, Hangzhou 310027, China)

Abstract: In order to study the inertial migration of neutrally buoyant particles (ρr=1)in a square duct, a parallel direct-forcing fictitious domain method was employed to perform fully-resolved numerical simulations. With the duct length (L=2H) and spherical particles of three different diameters, the migration trajectory and equilibrium positions at the bulk Reynolds number from 100 to 1500 were investigated and compared to the result of the pipe and channel. The effects of the particle diameters on the inertial migration were acquired. The results indicate that particles migrate to two main different kinds of equilibrium positions: one at the diagonal line near the corner and the other at the middle of center line. With the increasing of the Re, on one hand, the equilibrium position at the diagonal line becoms closer to the corner, besides the smaller the particle becomes, the closer to the corner; on the other hand, the equilibrium position at the center line tends to the wall first and then leaves the wall tending to the center while the Re increased to around 800. Comparatively the smaller the particle is, the closer to the wall the equilibrium positions is. Especially for the largest particle (a/H=0.15), the equilibrium position is similar to the tube′s inner equilibrium position.

Key words: fictitious domain method; inertial migration; particle-laden flows