Velocity overshoots in gradual contraction flows |
| |
Authors: | Robert J. Poole Manuel A. Alves |
| |
Affiliation: | 1. Department of Engineering, University of Liverpool, Brownlow Street, Liverpool L69 3GH, United Kingdom;2. Departamento de Engenharia Química, CEFT, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal |
| |
Abstract: | This study reports the results of a systematic numerical investigation, using the upper-convected Maxwell (UCM) and Phan-Thien–Tanner (PTT) models, of viscoelastic fluid flow through three-dimensional gradual planar contractions of various contraction ratios with the aim of investigating experimental observations of extremely large near-wall velocity overshoots in similar geometries [R.J. Poole, M.P. Escudier, P.J. Oliveira, Laminar flow of a viscoelastic shear-thinning liquid through a plane sudden expansion preceded by a gradual contraction, Proc. Roy. Soc. Lond. Ser. A 461 (2005) 3827]. We are able to obtain good qualitative agreement with the experiments, even using the UCM model in creeping-flow conditions, showing that neither inertia, second normal-stress difference nor shear-thinning effects are required for the phenomenon to be observed. Guided by the numerical results we propose a simple explanation for the occurrence of the velocity overshoots and the conditions under which they arise. |
| |
Keywords: | Viscoelastic flow in gradual contractions Cat's ears UCM model PTT model Creeping flow Finite-volume method |
本文献已被 ScienceDirect 等数据库收录! |
|