| taille du texte : S-M-L |
| impression | intranet

Assessment of a general equilibrium assumption for development of algebraic viscoelastic models

type de publication      article dans une revue internationale avec comité de lecture
date de publication 2007
auteur(s) Mompean Gilmar; Thais Laurent
journal (abréviation) Journal of Non-Newtonian Fluid Mechanics (J. Non-Newtonian Fluid Mech)
volume (numéro) 145 (1)
  
pages 41 – 51
résumé Abstract: The recent development of algebraic explicit stress models (AESM) for viscoelastic fluids rests upon a general equilibrium assumption, by invoking a slow variation condition on the evolution of the viscoelastic anisotropy tensor (the normalized deviatoric part of the extra-stress tensor, Mompean et al., J. Non-Newt. Fluid Mech., 111, 2003). This equilibrium assumption can take various forms depending on the general ob jective derivative which is used in the slow variation assumption. The purpose of the present paper is to assess the validity of the equilibrium hypothesis in different flow configurations. Viscometric flows (pure shear and pure elongation) are first considered to show that the Harnoy derivative (Harnoy, J. Fluid Mech., 3, 1976) is a suitable choice as an objective derivative that allows the algebraic models to retain the viscometric properties of the differential model from which they are derived. A creeping flow through a 4:1 planar contraction then serves as a benchmark for testing the equilibrium assumption in a flow exhibiting complex kinematics. Results of numerical simulations with the differential Oldroyd-B constitutive model allow to evaluate a posteriori the weight of extra-stress terms in different regions of the flow. Computations show that the equilibrium assumption making use of the Harnoy derivative is globally well verified. The assumption is exactly verified in flow regions of near-viscometric kinematics, whereas some departures are observed in the very near region of the corner entrance.
mots clés viscoelastic flows simulation; Algebraic explicit stress models;equilibrium assumption; 4:1 planar contraction; Finite volume method.
lien lien  
Exporter la citation au format CSV (pour Excel) ou BiBTeX (pour LaTeX).