Lubrication force model for a pendular liquid bridge of power-law fluid between two particles

Abstract

The validity of the lubrication force model on particles in the normal direction due to a pendular liquid bridge of power-law fluid based on the Reynolds lubrication theory is investigated by comparing it with Direct Numerical Simulation (DNS) results. It is found that the model can predict the force with less than 10% error when the dimensionless separation distance is smaller than 0.05. In the DNS results, a spike of the pressure at the edge of the bridge as well as a drop in pressure around the axis connecting the centres of the particles are observed on the particle surface. It is revealed that these phenomena are caused by the component of the viscous stress tensor which is neglected in the lubrication theory. A new closed-form solution of the lubrication force model is also proposed in this study which can be easily incorporated into the Discrete Element Method (DEM) framework.