Reis, T. and Wilson, H. J.
Rolie-Poly fluid flowing through constrictions: Two distinct
instabilities. Journal of Non-Newtonian Fluid Mechanics . (Submitted)
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.
|Subjects:||D - G > General|
|Research Groups:||Oxford Centre for Collaborative Applied Mathematics|
|Deposited By:||Peter Hudston|
|Deposited On:||04 Jul 2012 08:12|
|Last Modified:||29 May 2015 19:13|
Repository Staff Only: item control page