Experimental and numerical studies on pumping viscoplastic fluids

Abstract

Experimental and numerical studies were performed to investigate the pumping withdrawal of a Bingham plastic fluid using a vertical circular pipe. A Laponite suspension with 3% mass concentration was used for the experimental study. Results are compared with the theoretical solution of a point sink. A virtual point sink can be identified to exist below the intake along its centerline. With the assumption of an axisymmetric flow condition, radial velocity is found to be the same within a conical zone, but varies with the axial angle outside this zone in spherical polar coordinates. It was found that the flow viscosity and yield stress do not change the location of the virtual sink but they reduce the horizontal velocity of the Laponite suspension. The extent of the sheared flow region was also studied and the deformation radius was found to be proportional to the 1/3 power of the pumping rate.