The Mathematical Institute, University of Oxford, Eprints Archive

Rolie-Poly fluid flowing through constrictions: Two distinct
instabilities

Reis, T. and Wilson, H. J. (2012) Rolie-Poly fluid flowing through constrictions: Two distinct
instabilities.
Journal of Non-Newtonian Fluid Mechanics . (Submitted)

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Abstract

Elastic instabilities of entangled polymer melts are common in industrial processes but the physics responsible is not well understood. We present a numerical linear stability study of a molecular-based constitutive model which grants us physical insight into the underlying mechanics involved. Two constriction flows are considered - one shear dominated, the other extension dominated - and two distinct instabilities are found. The influence of the molecular structure and the behaviour of the polymer dynamics are investigated and in both cases chain relaxation and orientation play a crucial role. Additionally, convective-constraint release is also shown to be critical, but with a contrasting effect in the two flows: when the molecular weight is high, slow release is found to be stabilising in the extension dominated constriction but destabilising in the shear dominated flow. This suggests a molecular-based physical interpretation of the underlying mechanisms responsible for flow instabilities.

Item Type:Article
Subjects:D - G > General
Research Groups:Oxford Centre for Collaborative Applied Mathematics
ID Code:1526
Deposited By:Peter Hudston
Deposited On:04 Jul 2012 09:12
Last Modified:22 May 2013 11:00

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