Low-Re flow past an isolated cylinder with rounded corners

Handle URI:
http://hdl.handle.net/10754/617130
Title:
Low-Re flow past an isolated cylinder with rounded corners
Authors:
Zhang, Wei ( 0000-0002-3235-4861 ) ; Samtaney, Ravi ( 0000-0002-4702-6473 )
Abstract:
Direct numerical simulation is performed for flow past an isolated cylinder at Re=1,000. The corners of the cylinder are rounded at different radii, with the non-dimensional radius of curvature varying from R+=R/D=0.000 (square cylinder with sharp corners) to 0.500 (circular cylinder), in which R is the corner radius and D is the cylinder diameter. Our objective is to investigate the effect of the rounded corners on the development of the separated and transitional flow past the cylinder in terms of time-averaged statistics, time-dependent behavior, turbulent statistics and three-dimensional flow patterns. Numerical results reveal that the rounding of the corners significantly reduces the time-averaged drag and the force fluctuations. The wake flow downstream of the square cylinder recovers the slowest and has the largest wake width. However, the statistical quantities do not monotonically vary with the corner radius, but exhibit drastic variations between the cases of square cylinder and partially rounded cylinders, and between the latter and the circular cylinder. The free shear layer separated from the R+=0.125 cylinder is the most stable in which the first roll up of the wake vortex occurs furthest from the cylinder and results in the largest recirculation bubble, whose size reduces as R+ further increases. The coherent and incoherent Reynolds stresses are most pronounced in the near-wake close to the reattachment point, while also being noticeable in the shear layer for the square and R+=0.125 cylinders. The wake vortices translate in the streamwise direction with a convection velocity that is almost constant at approximately 80% of the incoming flow velocity. These vortices exhibit nearly the same trajectory for the rounded cylinders and are furthest away from the wake centerline for the square one. The flow past the square cylinder is strongly three-dimensional as indicated by the significant primary and secondary enstrophy, while it is dominated by the primary enstrophy (View the MathML source) for the rounded cylinders.
KAUST Department:
Mechanical Engineering; Physical Sciences and Engineering (PSE) Division
Citation:
Low-Re flow past an isolated cylinder with rounded corners 2016, 136:384 Computers & Fluids
Publisher:
Elsevier BV
Journal:
Computers & Fluids
Issue Date:
29-Jun-2016
DOI:
10.1016/j.compfluid.2016.06.025
Type:
Article
ISSN:
00457930
Sponsors:
The authors appreciate the valuable comments from the reviewers. The work was supported by the KAUST Office of Competitive Research Funds under Award No. URF/1/1394-01. The IBM Blue Gene/P Shaheen at KAUST was utilized for the simulations.
Additional Links:
http://linkinghub.elsevier.com/retrieve/pii/S0045793016302109
Appears in Collections:
Articles

Full metadata record

DC FieldValue Language
dc.contributor.authorZhang, Weien
dc.contributor.authorSamtaney, Ravien
dc.date.accessioned2016-07-18T09:24:56Z-
dc.date.available2016-07-18T09:24:56Z-
dc.date.issued2016-06-29-
dc.identifier.citationLow-Re flow past an isolated cylinder with rounded corners 2016, 136:384 Computers & Fluidsen
dc.identifier.issn00457930-
dc.identifier.doi10.1016/j.compfluid.2016.06.025-
dc.identifier.urihttp://hdl.handle.net/10754/617130-
dc.description.abstractDirect numerical simulation is performed for flow past an isolated cylinder at Re=1,000. The corners of the cylinder are rounded at different radii, with the non-dimensional radius of curvature varying from R+=R/D=0.000 (square cylinder with sharp corners) to 0.500 (circular cylinder), in which R is the corner radius and D is the cylinder diameter. Our objective is to investigate the effect of the rounded corners on the development of the separated and transitional flow past the cylinder in terms of time-averaged statistics, time-dependent behavior, turbulent statistics and three-dimensional flow patterns. Numerical results reveal that the rounding of the corners significantly reduces the time-averaged drag and the force fluctuations. The wake flow downstream of the square cylinder recovers the slowest and has the largest wake width. However, the statistical quantities do not monotonically vary with the corner radius, but exhibit drastic variations between the cases of square cylinder and partially rounded cylinders, and between the latter and the circular cylinder. The free shear layer separated from the R+=0.125 cylinder is the most stable in which the first roll up of the wake vortex occurs furthest from the cylinder and results in the largest recirculation bubble, whose size reduces as R+ further increases. The coherent and incoherent Reynolds stresses are most pronounced in the near-wake close to the reattachment point, while also being noticeable in the shear layer for the square and R+=0.125 cylinders. The wake vortices translate in the streamwise direction with a convection velocity that is almost constant at approximately 80% of the incoming flow velocity. These vortices exhibit nearly the same trajectory for the rounded cylinders and are furthest away from the wake centerline for the square one. The flow past the square cylinder is strongly three-dimensional as indicated by the significant primary and secondary enstrophy, while it is dominated by the primary enstrophy (View the MathML source) for the rounded cylinders.en
dc.description.sponsorshipThe authors appreciate the valuable comments from the reviewers. The work was supported by the KAUST Office of Competitive Research Funds under Award No. URF/1/1394-01. The IBM Blue Gene/P Shaheen at KAUST was utilized for the simulations.en
dc.language.isoenen
dc.publisherElsevier BVen
dc.relation.urlhttp://linkinghub.elsevier.com/retrieve/pii/S0045793016302109en
dc.rightsNOTICE: this is the author’s version of a work that was accepted for publication in Computers & Fluids. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Computers & Fluids, 29 June 2016. DOI: 10.1016/j.compfluid.2016.06.025en
dc.subjectDirect numerical simulationen
dc.subjectLow Reynolds numberen
dc.subjectTurbulenten
dc.subjectTransitionen
dc.subjectCylinderen
dc.subjectRounded corneren
dc.titleLow-Re flow past an isolated cylinder with rounded cornersen
dc.typeArticleen
dc.contributor.departmentMechanical Engineeringen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalComputers & Fluidsen
dc.eprint.versionPost-printen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorZhang, Weien
kaust.authorSamtaney, Ravien
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