Modelling PTFE paste extrusion: The effect of an objective flow type parameter

Mitsoulis, E; Hatzikiriakos, SG

dc.contributor.author	Mitsoulis, E	en
dc.contributor.author	Hatzikiriakos, SG	en
dc.date.accessioned	2014-03-01T01:31:14Z
dc.date.available	2014-03-01T01:31:14Z
dc.date.issued	2009	en
dc.identifier.issn	0377-0257	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19756
dc.subject	Axisymmetric contraction	en
dc.subject	Compressibility	en
dc.subject	Flow type parameter	en
dc.subject	Objectivity	en
dc.subject	Paste extrusion	en
dc.subject	Polytetrafluoroethylene	en
dc.subject	Slip law	en
dc.subject	Structural parameter	en
dc.subject.classification	Mechanics	en
dc.subject.other	Axisymmetric contraction	en
dc.subject.other	Flow type parameter	en
dc.subject.other	Objectivity	en
dc.subject.other	Paste extrusion	en
dc.subject.other	Slip law	en
dc.subject.other	Structural parameter	en
dc.subject.other	Compressibility	en
dc.subject.other	Dies	en
dc.subject.other	Ethylene	en
dc.subject.other	Extrusion	en
dc.subject.other	Extrusion dies	en
dc.subject.other	Fluid dynamics	en
dc.subject.other	Incompressible flow	en
dc.subject.other	Plastic flow	en
dc.subject.other	Rheology	en
dc.subject.other	Shrinkage	en
dc.subject.other	Strain rate	en
dc.subject.other	Flow simulation	en
dc.title	Modelling PTFE paste extrusion: The effect of an objective flow type parameter	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.jnnfm.2009.01.001	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.jnnfm.2009.01.001	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	In a recent article [P.D. Patil,JJ. Feng,S.G. Hatzikiriakos,Construtive modelling and flow simulation of polytetrafluoroethylene paste extrusion, J. Non-Newtonian Fluid Mech. 139 (2006). 44-53], a rheological constitutive equation was proposed to model the incompressible flow of poly-tetra-fluoro-ethylene (PTFE) paste and its structural development (fibrillation between the PTFE particles) during flow. The constitutive model was a combination of shear-thinning and shear-thickening viscosity terms, depending on a structural parameter, xi which obeyed a convective-transport equation. In the latter. a non-objective flow type parameter, psi, was employed, which depended on the magnitudes of the rate-of-strain and vorticity tensors. In the present work, an objective flow type parameter is used instead [R.G. Larson, Flows of constant stretch history for polymeric materials with power-law distributions of relaxation times, Rheol. Acta 24 (1985), 443-449]. Despite its complexity and the severe slip at the wall, good convergence has been obtained even for very high apparent shear rates. New results are shown as Contours of the xi-parameter in the flow field as well as Contours of the new objective flow type parameter. psi*, and compared with previous results. It is shown that the corrected model predicts higher structural levels (more fibrils) in PTFE paste How through extrusion (ties and that the new results are more consistent with experimental observations. (C) 2009 Elsevier B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	Journal of Non-Newtonian Fluid Mechanics	en
dc.identifier.doi	10.1016/j.jnnfm.2009.01.001	en
dc.identifier.isi	ISI:000266182200006	en
dc.identifier.volume	159	en
dc.identifier.issue	1-3	en
dc.identifier.spage	41	en
dc.identifier.epage	49	en