Viscoelastic flow through gradual contractions: Experiments and simulations

Abstract

This paper reports the results of an experimental investigation into the flow of aqueous solutions of a polyacrylamide at three concentrations through a curved gradual planar contraction with a contraction ratio of 8:1. Poole et al. (R.J. Poole et al (2005) Proc. R. Soc. London A vol. 461) have previously observed large velocity overshoots near to the sidewalls of a gradual contraction while investigating the flow of a viscoelastic shear-thinning fluid through a sudden expansion preceded by a smooth gradual contraction. These overshoots were termed 'cat's ears' due to their appearance. Experimental results are presented here that conflrm the occurrence of these overshoots within the contraction section without the presence of a sudden expansion at its outlet. Preliminary numerical results that exhibit qualitative agreement with the experimental results are also presented.