Benchmark solutions for the flow of Oldroyd-B and PTT fluids in planar contractions

Abstract

The paper presents very accurate numerical results for the vortex size, the vortex intensity and the Couette correction, in planar contraction flows of Oldroyd-B and PTT fluids (ε=0.25) with both the linear and the exponential stress function, and with a solvent viscosity ratio equal to 1/9. The accuracy of these results is quantified, being generally below 1% (0.3% for most results), and the finest mesh employed had over 1 million degrees of freedom. Such degree of mesh fineness is shown to be required for accurate results with the Oldroyd-B fluid, especially at high Deborah numbers, but the shear-thinning PTT fluid in general does not require the finest meshes. In terms of level of elasticity, steady results for the PTT fluid could be obtained for values of the Deborah number in excess of 100 (linear PTT) and 10,000 (exponential PTT). © 2003 Elsevier Science B.V. All rights reserved.