Abstract: For micro effect of the slippage phenomenon adjacent to wall in micro-scale gap flow of hydraulic system, computational fluid dynamics (CFD) method is applied to investigate the effects of wall slip on flow behaviors in micro-scale gap. The Navier slip boundary condition, which wall slip velocity is proportional to the degree of slip coefficient and the local velocity gradient, is adopted to simulate the gap flow between oil sealing sides in hydrostatic bearing system. After examining consistency of results between simulation and theory, the influence of slip parameter on gap flow behavior is implemented. The influence of wall apparent viscosity coefficient, temperature-viscosity characteristic and Non-Newtonian behavior on distributions of flow in gap and the value of wall slip velocity are analyzed deeply. It is shown that micro-scale gap flow with slip condition is different from that of no-slip boundary condition, when the wall material property coefficient  =0.01, the faster of the wall slip velocity and more uniform of velocity in flow gap, and the temperature-viscosity characteristic is the significant factor affecting gap flow distribution and slip velocity.

Key words: Boundary slip, Gap flow, Navier slip, Oil film, Cone crusher Inter-particle breakage Particle shape transformation Effect flakiness index