Abstract: Based on the ‘Galileo Principle of Relativity’, a numerical model is proposed to describe the quasi-stationary motion of a particle in a straight pipe, by which the inertial lift is numerically obtained on the spherical particle inside a straight micro-channel with squared section, combined by computational fluid dynamics(CFD) technique. The spatial distribution of the inertial lift is numerically investigated and the influence on the inertial force is also obtained by the particle’s diameter. Results indicate, the inertial lift shows an obvious regularity in spatial distribution: it is towards the channel wall in the vicinity of the channel axis with its magnitude increasing firstly to the maximum and then gradually decreasing to zero in radial direction while it is towards the channel axis in the vicinity of the channel wall with its magnitude increasing sharply close to the channel wall. There is a unique position with zero inertial lift in radial direction, which is just the position of ‘Inertial Focus of Particles’. The inertial force consists of two components, one is the viscous stress, the other is the pressure stress, but the latter is the determinant to ‘Inertial Focus of Particles’. These results help to perfect the mechanical mechanism on the solid-liquid flow field with low Reynolds number and enhance the further commercial applications of the ‘Inertial Focus of Particles’.

Key words: inertial focus of particles;inertial lift;microfluidics;numerical investigation