Global destabilization of flow over a backward-facing step

Kaiktsis, L; Monkewitz, PA

dc.contributor.author	Kaiktsis, L	en
dc.contributor.author	Monkewitz, PA	en
dc.date.accessioned	2014-03-01T01:53:07Z
dc.date.available	2014-03-01T01:53:07Z
dc.date.issued	2003	en
dc.identifier.issn	1070-6631	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/26861
dc.subject.classification	Mechanics	en
dc.subject.classification	Physics, Fluids & Plasmas	en
dc.subject.other	SPATIALLY DEVELOPING FLOWS	en
dc.subject.other	TURBULENT FLOWS	en
dc.subject.other	CONVECTIVE INSTABILITIES	en
dc.subject.other	DYNAMICS	en
dc.subject.other	WAKES	en
dc.subject.other	NONPARALLEL	en
dc.subject.other	ABSOLUTE	en
dc.subject.other	LAMINAR	en
dc.title	Global destabilization of flow over a backward-facing step	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	Global destabilization of two-dimensional flow over a backward-facing step embedded in a channel, i.e., flow in a plane channel with a sudden expansion, is investigated by numerical simulations using a spectral element method. In the low Reynolds number regime where the two-dimensional flow is steady without manipulation, self-excited oscillations of the entire flow are induced by appropriate simultaneous suction at the step face and blowing at the wall adjacent to the step. The boundary between steady and time-dependent (destabilized) flow is determined as a function of the streamwise extent of the blowing region and its position relative to the step, for an expansion ratio of approximately two, a Reynolds number fixed at Re=1000, and equal suction and blowing mass flow rates. The computed periodic, globally synchronized flow regimes are characterized using instantaneous streamline patterns, time traces of physical quantities, and proper orthogonal decomposition of the velocity fields. The global flow behavior is also related to the absolute instability properties of the local streamwise velocity profiles. Preliminary three-dimensional simulations finally suggest that the 2-D unsteady flows obtained in the present study are, in general, susceptible to three-dimensional secondary instabilities. Nevertheless, the first experiments suggest that the 2-D analysis provides a qualitatively correct description of the flow transitions and that practical applications of this wall-blowing and -suction scheme, such as mixing enhancement, may be feasible. (C) 2003 American Institute of Physics.	en
heal.publisher	AMER INST PHYSICS	en
heal.journalName	PHYSICS OF FLUIDS	en
dc.identifier.isi	ISI:000186509900007	en
dc.identifier.volume	15	en
dc.identifier.issue	12	en
dc.identifier.spage	3647	en
dc.identifier.epage	3658	en