An Experimental Study Of Yield Stress Fluid Displacement Flows In A Moving Annulus

In this paper, the displacement flow of a viscoplastic fluid by a non-Newtonian fluid in a vertical annulus is experimentally studied. The two fluids have a very small density difference. The light displaced fluid is placed below the heavy displacing fluid. Buoyancy, the imposed flow velocity and the annulus motion are the important flow parameters. In regard to the annulus motion, two scenarios are considered: first, the annulus is stationary; Second, the annulus slowly reciprocates with an amplitude of 100 mm and the frequency of 0.1 Hz. Our experimental results demonstrate that the displacement flow efficiency increases significantly when the annulus is in motion.