A novel suspension transport method: Viscoplastic lubrication of high-density fluids

We present proof-of-concept experiments to illustrate the application of viscoplastic lubrication in transport of high-concentration suspensions. The proposed transport method appears robust for a wide range of suspension concentrations. We develop a theoretical description of the flow that incorporates the significant density difference between the suspension and the lubricating fluid. We explore the variation of the pressure gradient and the flow rate ratio with fluid properties and demonstrate that buoyancy effects expand the favorable lubrication regime within the phase space of the problem. We illustrate the possibility of flow reversal in the core fluid and the emergence of a new flow regime, two features not captured when buoyancy stresses are neglected.