Linear instabilities in the wakes of cylinders with triangular cross-sections

Z. Y. Ng, T. Vo, W. K. Hussam, G. J. Sheard

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Abstract

The wakes of flows past bluff bodies are known to undergo several transitions leading to turbulence, each incurring changes to the dynamics of the flow. The initial transition to three-dimensional flow for several cylindrical geometries manifests as coherent structures along the cylinder span and have been the focus of many investigations. This transition and its associated instability modes are investigated numerically for flows past a cylinder with triangular cross-section at various inclinations using Floquet stability analysis. The instabilities are shown to be strongly dependent on the cylinder inclination, producing a dominant synchronous instability mode consistent with the synchronous Mode A and the subharmonic Mode C at various cylinder inclinations. The neutral stability threshold ranges approximately from 100 < Reh < 140, where h is the projected frontal height of the cylinder; and the wavelengths of the instabilities ranging approximately between 4h–6h for the synchronous mode and approximately 2h for the subharmonic mode at transition for various cylinder inclinations.

Original languageEnglish
Title of host publicationProceedings of the 20th Australasian Fluid Mechanics Conference, AFMC 2006
Place of PublicationPerth WA
PublisherAustralasian Fluid Mechanics Society
Number of pages4
ISBN (Electronic)9781740523776
Publication statusPublished - 2016
EventAustralasian Fluid Mechanics Conference 2016 - The University of Western Australia, Perth, Australia
Duration: 5 Dec 20168 Dec 2016
Conference number: 20th

Publication series

NameProceedings of the 20th Australasian Fluid Mechanics Conference, AFMC 2016

Conference

ConferenceAustralasian Fluid Mechanics Conference 2016
Abbreviated titleAFMC 2016
CountryAustralia
CityPerth
Period5/12/168/12/16

Cite this

Ng, Z. Y., Vo, T., Hussam, W. K., & Sheard, G. J. (2016). Linear instabilities in the wakes of cylinders with triangular cross-sections. In Proceedings of the 20th Australasian Fluid Mechanics Conference, AFMC 2006 [630] (Proceedings of the 20th Australasian Fluid Mechanics Conference, AFMC 2016). Australasian Fluid Mechanics Society. http://people.eng.unimelb.edu.au/imarusic/proceedings/20/630%20Paper.pdf