On modelling viscoelastic flow through abrupt circular 8:1 contractions – matching experimental pressure-drops and vortex structures

• Published in: Journal of non-Newtonian fluid mechanics 2018-01, Vol.251, p.28-42
• Main Authors: Tamaddon-Jahromi, H.R., López-Aguilar, J.E., Webster, M.F.
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Constitutive models; Flow velocity; Fluid flow; Mathematical models; Parameters; Parametric analysis; Rheological properties; Viscoelasticity; Vortices
• ISSN: 0377-0257; 1873-2631
• DOI: 10.1016/j.jnnfm.2017.11.006

This study compares and contrasts computational predictions against experimental data for some viscoelastic contraction flows. Nigen and Walters [1], provides the comparative data-set, the specific flow of interest is an 8:1 abrupt circular contraction, and the constitutive model is that of swanINNFM(q) [swIM]. Taken against increasing flow-rate, such a model is observed to capture significant vortex-enhancement in these axisymmetric flows, reflecting well the counterpart experimental findings. In addition, rich vortex characteristics are reflected, through evolving patterns of salient-corner, lip-vortex and elastic-corner vortices. A systematic parametric analysis is conducted over three independent and governing material parameters in the model, whilst attempting to interpret rheological adjustment against such changes in flow-structure. Specifically, this has involved variation in solvent-fraction (β), finite-extensibility parameter (L), and extensional-based dissipative parameter (λD).