Bagley correction: The effect of contraction angle and its prediction

Mitsoulis, E; Hatzikiriakos, SG

dc.contributor.author	Mitsoulis, E	en
dc.contributor.author	Hatzikiriakos, SG	en
dc.date.accessioned	2014-03-01T01:18:44Z
dc.date.available	2014-03-01T01:18:44Z
dc.date.issued	2003	en
dc.identifier.issn	0035-4511	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15164
dc.subject	Bagley correction	en
dc.subject	Contraction angle	en
dc.subject	End effects	en
dc.subject	K-BKZ and Cross constitutive models	en
dc.subject.classification	Mechanics	en
dc.subject.other	capillary flow	en
dc.subject.other	contraction	en
dc.subject.other	mathematical modeling	en
dc.subject.other	polymer melt	en
dc.subject.other	viscoelasticity	en
dc.subject.other	viscosity	en
dc.title	Bagley correction: The effect of contraction angle and its prediction	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s00397-003-0294-y	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s00397-003-0294-y	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	The excess pressure losses due to end effects (mainly entrance) in the capillary flow of a branched polypropylene melt were studied both experimentally and theoretically. These losses were first determined experimentally as a function of the contraction angle ranging from 10degrees to 150degrees. It was found that the excess pressure loss function decreases for the same apparent shear rate with increasing contraction angle from 10degrees to about 45degrees, and consequently slightly increases from 45degrees up to contraction angles of 150degrees. Numerical simulations using a multimode K-BKZ viscoelastic and a purely viscous (Cross) model were used to predict the end pressures. It was found that the numerical predictions do agree well with the experimental results for small contraction angles up to 30degrees. However, the numerical simulations under-predict the end pressure for larger contraction angles. The effects of viscoelasticity, shear, and elongation on the numerical predictions are also assessed in detail. Shear is the dominant factor controlling the overall pressure drop in flows through small contraction angles. Elongation becomes important at higher contraction angles (greater than 45degrees). It is demonstrated in abrupt contractions (angle of 180degrees) that both the entrance pressure loss and the vortex size are strongly dependent on the extensional viscosity for this branched polymer. It is suggested that such an experiment (visualisation of entrance flow) can be useful in evaluating the validity of constitutive equations and it can also be used to fitting parameters of rheological models that control the elongational viscosity.	en
heal.publisher	SPRINGER-VERLAG	en
heal.journalName	Rheologica Acta	en
dc.identifier.doi	10.1007/s00397-003-0294-y	en
dc.identifier.isi	ISI:000184017800003	en
dc.identifier.volume	42	en
dc.identifier.issue	4	en
dc.identifier.spage	309	en
dc.identifier.epage	320	en