Abstract: Sedimentation of micro particles in a narrow microchannel was simulated with multiple-relaxation-time lattice Boltzmann model. Influence of gas rarefaction, initial position of particle and interaction between particles on sedimentation process is analyzed. It is found that gas rarefaction effect becomes obvious with increase of Knudsen number. And the effective viscosity of gas is decreased. At the same time, slip velocity on the surface of particle increases and viscosity resistance of particle decreases, which results in an increase of particle equilibrium velocity. For different initial positions of particle, there exists a significant difference in sedimentation process. It reveals that horizontal motion of micro particle exists besides moving in the vertical direction. And the particle has oscillating tendency before stabilizing on the central position in horizontal direction. For DKT phenomenon in microscale, rarefaction effect is obvious on trajectory of particles and the drafting process is prolonged.

Key words: particle sedimentation, rarefaction effect, slip velocity, DKT, lattice Boltzmann method