The flow behavior of the liquid/powder mixture, theory and experiment II: Effect of the friction force

The analytical theoretical formula for calculating the unconfined yield shear strength (fc) of the powder/oil mixture obtained earlier in our previous paper [1] is modified, taking into account the work required not only to rupture the liquid bridge, but also to move particles relative to each other against the inter-particle friction force. This formula is valid for powder/oil mixtures with homogeneously distributed oil, as well as for dry powders. Experimental results obtained for dry narrowly sized silica particles in a Schulze cell agree with the developed formula, suggesting experimental value for the friction coefficient and accounting for the effect of the roughness on the adhesion and friction forces.

The formula for calculating unconfined yield shear strength (fc) of the powder/oil mixture is developed taking into account the work required to rupture liquid bridges and movement of particles relative to each other against inter-particle friction forces. Experimental results obtained for dry narrowly sized silica particles, or for a silica/oil mixture in a Schulze cell, agree with this developed formula.Points are the experimental results for silica with R = 50 µm and oil; the solid line is theoretical equation developed in the present paper.Figure optionsDownload as PowerPoint slide