Axial and secondary flow study in a 90 deg bifurcation under pulsating conditions using PIV

Nikolaidis, NM; Mathioulakis, DS

dc.contributor.author	Nikolaidis, NM	en
dc.contributor.author	Mathioulakis, DS	en
dc.date.accessioned	2014-03-01T01:17:34Z
dc.date.available	2014-03-01T01:17:34Z
dc.date.issued	2002	en
dc.identifier.issn	0098-2202	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14568
dc.subject	Secondary Flow	en
dc.subject.classification	Engineering, Mechanical	en
dc.subject.other	Acceleration	en
dc.subject.other	Bifurcation (mathematics)	en
dc.subject.other	Deceleration	en
dc.subject.other	Flow patterns	en
dc.subject.other	Kinematics	en
dc.subject.other	Reynolds number	en
dc.subject.other	Viscosity	en
dc.subject.other	Deg bifurcation	en
dc.subject.other	Secondary flow	en
dc.subject.other	Secondary velocity	en
dc.subject.other	Shear layer	en
dc.subject.other	Axial flow	en
dc.title	Axial and secondary flow study in a 90 deg bifurcation under pulsating conditions using PIV	en
heal.type	journalArticle	en
heal.identifier.primary	10.1115/1.1470478	en
heal.identifier.secondary	http://dx.doi.org/10.1115/1.1470478	en
heal.language	English	en
heal.publicationDate	2002	en
heal.abstract	Both axial and secondary flow were experimentally studied in a 90-degree bifurcation of square tubes, under pulsating conditions and equal branch flow rates. The examined peak Reynolds number (Re) was in the range 330-830, and the Womersley parameter (a) between 5 and 15. In the extension of the mother tube during deceleration, axial flow separated from the wall opposite of the 90-degree branch. The formed shear layer rolled up, for higher values of Re and low α, generating discrete vortices. However, for the highest value of α, the shear layer was limited close to the wall, without rolling up, for all the examined Re. During acceleration, all recirculation zones were washed out and the flow became attached before flow peak. In the 90-degree branch during acceleration, a vortex was formed at the bifurcation apex and moved streamwise towards the center of the cross-section where it degenerated. The secondary flow of this branch had the following characteristics: during deceleration two Dean vortices were located close to the outer bend side of the cross-section, and their strength was progressively reduced. A little before flow peak any Dean vortices of the previous phase were destroyed and two new ones were born. Maximum secondary velocities were on the order of 20% higher than the bulk velocity of the branch.	en
heal.publisher	ASME-AMER SOC MECHANICAL ENG	en
heal.journalName	Journal of Fluids Engineering, Transactions of the ASME	en
dc.identifier.doi	10.1115/1.1470478	en
dc.identifier.isi	ISI:000175984400025	en
dc.identifier.volume	124	en
dc.identifier.issue	2	en
dc.identifier.spage	505	en
dc.identifier.epage	511	en