有壁面滑移时刚性球颗粒间流体的挤压流动

挤压流动中流体在壁面的滑移发生在某些非牛顿流体或存在润滑层的牛顿流体情形,此现象对黏性力的影响值得研究。基于润滑理论,导出了壁面滑移时刚性球间牛顿流体挤压流动的压力分布和黏性力的解析解。通过引进滑移修正系数,解析解可分解成无滑移解和滑移修正系数的乘积。该系数是滑移参数和量纲1积分上限的复杂函数,但数值试验表明,对充分大的量纲1积分上限和给定的滑移参数,该系数趋于常数,由此可大大简化黏性力的计算,从而明显减小湿散体离散元模拟的计算量。

On the Squeeze Flow of Newtonian Fluid Between Two Rigid Spheres With Wall Slip

In a squeeze flow wall slip may happen at a solid fluid interface in the case of some Non Newtonian fluid, or a Newtonian fluid with a thin lubricant film between the fluid and the wall. Based on Reynolds' lubrication theory, an analytical solution for two rigid spheres was derived, including pressure distribution and resulting viscous force. By introducing a so called "slip correction coefficient", this force can be represented by a product of the relevant non slip solution and the coefficient. In general this coefficient is a function of the slip parameter and the dimensionless integration limit, however, further numerical test shows that, for a sufficient large value of the dimensionless upper limit of integration and a given slip parameter, the coefficient converges to a limit value, suggesting a simplification in calculation of the viscous force to save the CPU time significantly in simulation for a wet granule system using the Distinct Element Method.