Assessment of secondary bubble formation on a backward-facing step geometry

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dc.contributor.author Juste, G.L.
dc.contributor.author Fajardo Peña, Pablo
dc.contributor.author Guijarro, A.
dc.date.accessioned 2019-09-23T13:32:30Z
dc.date.available 2019-09-23T13:32:30Z
dc.date.issued 2016-07-01
dc.identifier.bibliographicCitation Physics of fluids 28, 7(074106), 25 pp.
dc.identifier.issn 1070-6631
dc.identifier.issn 1089-7666 (online)
dc.identifier.uri http://hdl.handle.net/10016/28872
dc.description.abstract Flow visualization experiments and numerical simulations were performed on a narrow three-dimensional backward-facing step (BFS) flow with the main objective of characterizing the secondary bubble appearing at the top wall. The BFS has been widely studied because of its geometrical simplicity as well as its ability to reproduce most of the flow features appearing in many applications in which separation occurs. A BFS test rig with an expansion ratio of 2 and two aspect ratios (AR = 4 and AR = 8) was developed. Tests were performed at range of Reynolds numbers ranging from 50 to 1000; visualization experiments provided a qualitative description of secondary bubble and wall-jet flows. Large eddy simulations were carried out with two different codes for validation. Numerical solutions, once validated with experimental data from the literature, were used to acquire a deeper understanding of the experimental visualizations, to characterize the secondary bubble as a function of the flow variables (Reynolds and AR) and to analyze the effect of the secondary bubble on primary reattachment length. Finally, to decouple the sidewall effects due to the non-slip condition and the intrinsic flow three-dimensionality, numerical experiments with free-slip conditions over the sidewalls were computed. The main differences were as follows: When the non-slip condition is used, the secondary bubble appears at a Reynolds number of approximately 200, increases with the Reynolds number, and is limited to a small part of the span. This recirculation zone interacts with the wall-jets and causes the maximum and minimum lengths in the reattachment line of the primary recirculation. Under free slip conditions, the recirculation bubble appears at a higher Reynolds number and covers the entire channel span. Published by AIP Publishing.
dc.format.extent 25
dc.language.iso eng
dc.publisher AIP Publishing
dc.rights © 2016 AIP Publishing
dc.subject.other Laminar-flow
dc.subject.other Numerical simulations
dc.subject.other Recirculating-flows
dc.subject.other Reattachment
dc.subject.other Instability
dc.subject.other Dynamics
dc.subject.other Adjacent
dc.subject.other Channel
dc.subject.other Vortex
dc.subject.other Model
dc.title Assessment of secondary bubble formation on a backward-facing step geometry
dc.type article
dc.subject.eciencia Física
dc.identifier.doi https://doi.org/10.1063/1.4958723
dc.rights.accessRights openAccess
dc.type.version publishedVersion
dc.identifier.publicationfirstpage 1
dc.identifier.publicationissue 7
dc.identifier.publicationlastpage 25
dc.identifier.publicationtitle PHYSICS OF FLUIDS
dc.identifier.publicationvolume 28
dc.identifier.uxxi AR/0000018194
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