Effect of Viscoelasticity in Fountain Flow of Polyethylene Melts

Mitsoulis, E

dc.contributor.author	Mitsoulis, E	en
dc.date.accessioned	2014-03-01T01:30:17Z
dc.date.available	2014-03-01T01:30:17Z
dc.date.issued	2009	en
dc.identifier.issn	0930-777X	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19531
dc.subject	Polyethylene	en
dc.subject.classification	Engineering, Chemical	en
dc.subject.classification	Polymer Science	en
dc.subject.other	INTEGRAL CONSTITUTIVE EQUATION	en
dc.subject.other	FINITE-ELEMENT SIMULATION	en
dc.subject.other	FREE-SURFACE FLOWS	en
dc.subject.other	NUMERICAL-SIMULATION	en
dc.subject.other	EXTRUDATE-SWELL	en
dc.subject.other	ENTRY FLOW	en
dc.subject.other	MOLD	en
dc.subject.other	ORIENTATION	en
dc.subject.other	EXTRUSION	en
dc.subject.other	MOTION	en
dc.title	Effect of Viscoelasticity in Fountain Flow of Polyethylene Melts	en
heal.type	journalArticle	en
heal.identifier.primary	10.3139/217.2295	en
heal.identifier.secondary	http://dx.doi.org/10.3139/217.2295	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	Fountain flow is the phenomenon of deceleration and outward motion of fluid particles as they approach a slower moving interface. Numerical simulations have been undertaken for the flow of viscoelastic fluids, obeying an integral constitutive equation of the K-BKZ type, capable of describing the behavior of polymer melts. Two polyethylene melts are considered, a branched LDPE and a linear HDPE. Their rheology is well captured by the integral model. The flow simulations are performed for planar and axisymmetric geometries and show the shape and extent of the free surface, as well as the stresses and pressures in the system. The semicircle is a good rough approximation for the free surface of fountain flow, but detailed computations show the effect of elasticity on the free surface, which is non-monotonic for the LDPE as the elasticity level (or apparent shear rate) increases. The less elastic HDPE shows a monotonic decrease in the extent of the flow front as elasticity increases. In all cases, the excess pressure losses (front pressure correction) increase with increasing flow rate. The effect of a non-zero second normal stress difference is to extend the flow front and increase the pressure losses.	en
heal.publisher	CARL HANSER VERLAG	en
heal.journalName	INTERNATIONAL POLYMER PROCESSING	en
dc.identifier.doi	10.3139/217.2295	en
dc.identifier.isi	ISI:000271401400008	en
dc.identifier.volume	24	en
dc.identifier.issue	5	en
dc.identifier.spage	439	en
dc.identifier.epage	451	en