Newtonian and non-Newtonian flow near a re-entrant corner

TLDR: In this paper, the authors used the laser Doppler technique to study flow characteristics in the vicinity of a reentrant corner for both Newtonian and elastic liquids, and found that near the reenterrant corner the flow characteristics are virtually independent of both fluid inertia and fluid elasticity.

Abstract: The Laser Doppler technique is used to study flow characteristics in the vicinity of a re-entrant corner for both Newtonian and elastic liquids. An L-shaped channel is chosen as the test geometry and a constant-viscosity Boger fluid as the elastic liquid. It is found that near the re-entrant corner the flow characteristics are virtually independent of both fluid inertia and fluid elasticity. The observed influence of fluid inertia is in agreement with existing theoretical predictions, whilst that of fluid elasticity is consistent with the elastic liquid behaving asymptotically like a Newtonian viscous liquid near the corner, suggesting the use of Oldroyd- (rather than Maxwell-) type models in future simulation studies. Numerical predictions for the Newtonian cases using finite-difference techniques are in satisfactory agreement with experiment, whilst those for an Oldroyd model are in qualitative agreement with experiment results for the Boger fluid.