Viscoelastic simulations using the closed-form Adaptive Length Scale (ALS-C) model

Zografos, Konstantinos, Afonso, Alexandre M and Poole, Robert J ORCID: 0000-0001-6686-4301
(2022) Viscoelastic simulations using the closed-form Adaptive Length Scale (ALS-C) model. JOURNAL OF NON-NEWTONIAN FLUID MECHANICS, 304. p. 104776.

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In this paper we employ the closed-form of the Adaptive Length Scale Model (ALS-C) [Ghosh et al., “A new model for dilute polymer solutions in flows with strong extensional components”, J. Rheol. 46, 1057–1089 (2002)] and we investigate its characteristics and potential to more accurately capture pressure-drop in contraction flows of viscoelastic fluids. The ALS-C model was originally derived based on purely homogeneous elongational flows in order to model coil-stretch hysteresis. However, in its originally proposed form we reveal a number of numerical issues which have not been analysed previously and are reported here considering both standard rheological flows, simple channel flows and complex flows within a 4:1 contraction. We demonstrate a new approach for evaluating the instantaneous change in the adaptive length scale as a result of instantaneous changes in the flow field, overcoming the need to employ other root-finding approaches. Guidelines are provided for the correct use of the employed local Weissenberg number and a modified approach is considered for the evolution equation of the actual extensibility, allowing its efficient use in complex numerical simulations. We illustrate that a suitable combination of the model parameters can produce behaviours that are found experimentally in viscoelastic fluids and we find that pressure-drop enhancements in flows within 4:1 contractions observed experimentally are achievable.

Item Type: Article
Uncontrolled Keywords: Adaptive Length Scale, Contraction flows, Elongational flows, Shear flows, Viscoelastic fluids
Divisions: Faculty of Science and Engineering > School of Engineering
Depositing User: Symplectic Admin
Date Deposited: 15 Jun 2022 08:55
Last Modified: 18 Jan 2023 20:59
DOI: 10.1016/j.jnnfm.2022.104776
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