Extrudate swell of Boger fluids

Mitsoulis, E

dc.contributor.author	Mitsoulis, E	en
dc.date.accessioned	2014-03-01T01:33:29Z
dc.date.available	2014-03-01T01:33:29Z
dc.date.issued	2010	en
dc.identifier.issn	0377-0257	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20443
dc.subject	Boger fluids	en
dc.subject	Exit correction	en
dc.subject	Extrudate swell	en
dc.subject	Free surface	en
dc.subject	Gravity flows	en
dc.subject	Viscoelasticity	en
dc.subject.classification	Mechanics	en
dc.subject.other	Axisymmetric geometries	en
dc.subject.other	Boger fluids	en
dc.subject.other	Dilute polymer solutions	en
dc.subject.other	Excess pressure	en
dc.subject.other	Extrudate swell	en
dc.subject.other	Extrudates	en
dc.subject.other	Free surfaces	en
dc.subject.other	Free-surface gravity	en
dc.subject.other	Integral model	en
dc.subject.other	Normal stress	en
dc.subject.other	Numerical simulation	en
dc.subject.other	Shear rates	en
dc.subject.other	Stress difference	en
dc.subject.other	Stress ratio	en
dc.subject.other	Computer simulation	en
dc.subject.other	Elasticity	en
dc.subject.other	Shear deformation	en
dc.subject.other	Surfaces	en
dc.subject.other	Viscoelasticity	en
dc.subject.other	Viscosity	en
dc.subject.other	Fluids	en
dc.title	Extrudate swell of Boger fluids	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.jnnfm.2010.04.011	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.jnnfm.2010.04.011	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	Boger fluids are dilute polymer solutions exhibiting high elasticity at low apparent shear rates, which leads to high extrudate swell. Numerical simulations have been undertaken for the flow of three Boger fluids (including benchmark Fluid M1), obeying an integral constitutive equation of the K-BKZ type, capable of describing the behavior of dilute polymer solutions. Their rheology is well captured by the integral model. The flow simulations are performed for planar and axisymmetric geometries without or with gravity. The results provide the extrudate swell and the excess pressure losses (exit correction), as well as the shape and extent of the free surface. All these quantities increase rapidly and monotonically with increasing elasticity level measured by the stress ratio, S-R. It was found that the main reason for the high extrudate swelling is high normal stresses exhibited in shear flow (namely, the first normal-stress difference, N-1). Surprisingly, the elongational parameter of the model or a second normal-stress difference N-2 do not affect the results appreciably. Gravity serves to lower the swelling considerably, and makes the simulations easier and in overall agreement with previous experiments. (C) 2010 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.2010.04.011	en
dc.identifier.isi	ISI:000279193900011	en
dc.identifier.volume	165	en
dc.identifier.issue	13-14	en
dc.identifier.spage	812	en
dc.identifier.epage	824	en