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Modelling polymeric flows in reverse roll coating processes with dynamic wetting lines and air-entrainment: FENE and PTT solutions

S.O.S. Echendu, H.R. Tamaddon-Jahromi, M.F. Webster, Michael Webster Orcid Logo

Journal of Non-Newtonian Fluid Mechanics, Volume: 214, Pages: 38 - 56

Swansea University Author: Michael Webster Orcid Logo

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DOI (Published version): 10.1016/j.jnnfm.2014.09.013

Abstract

Viscoelastic FENE and PTT constitutive models are considered in the simulation of high-speed reverse roll coating flow with polymeric paint solutions, where wetting lines and air-entrainment are incorporated. Both FENE-CR and FENE-P models are utilised to illustrate the influence of shear-thinning i...

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Published in: Journal of Non-Newtonian Fluid Mechanics
Published: 2014
URI: https://cronfa.swan.ac.uk/Record/cronfa24189
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Abstract: Viscoelastic FENE and PTT constitutive models are considered in the simulation of high-speed reverse roll coating flow with polymeric paint solutions, where wetting lines and air-entrainment are incorporated. Both FENE-CR and FENE-P models are utilised to illustrate the influence of shear-thinning in the context of strain-hardening properties. Strain-softening is introduced via PTT solutions in contrast. Steady solutions are derived numerically through a time-stepping hybrid finite element-finite volume sub-cell algorithm with dynamic free-surface location, drawing upon a fractional staged, predictor-corrector, and semi-implicit time-stepping procedure. A systematic computational and rheological study allows for parametric variation in elasticity (Wi-variation), level of strain-hardening (AL), shear-thinning and solvent fraction (β). Various problem aspects are investigated to reveal the influence of viscoelasticity on vortex developments, pressure and lift profiles, shear and strain-rates, and critical stress states. Specific features of viscoelastic flow response are observed by analysing stress and flow structures over a range of Weissenberg numbers. The novel aspects of the work lie in the application of the algorithm to the reverse roll coating process under such viscoelastic fluid models.
Keywords: Reverse roll coating, dynamic wetting, finite element/finite volume sub-cell, viscoelastic FENE models, shear and extensional flow.
College: Faculty of Science and Engineering
Start Page: 38
End Page: 56