Measurement of pressure loss and flow visualization in the flow of viscoelastic fluids through cylinder arrays

The viscoelastic flow through the rectangular duct containing cylinder array, which is one of the model channels of porous media,is examined experimentally. Test fluids used are 0.01wt%, 0.1wt%, and 1.0wt% aqueous solutions of polyacrylamide (PAA). In the measurement of pressure loss, the excess pressure loss occurs as reported for the flow in the porous media. It is found that the onset of the excess pressure loss is related to the stretch-thickening property in the elongational viscosity of the PAA solution and also depends on the polymer concentration and the channel geometry. Furthermore, the flow patterns in the cylinder arrays, which include the converging-diverging and winding flow, suggest that the occurrence of excess pressure loss is caused by the elongational property for the PAA solutions.