WSEAS Transactions on Systems and Control

Print ISSN: 1991-8763
E-ISSN: 2224-2856

Volume 12, 2017

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

Volume 12, 2017

Numerical Study of a Separated Boundary Layer Transition over Two and Three Dimensional Geometrical Shapes

AUTHORS: Hayder Azeez Diabil, Xin Kai Li, Ibrahim Elrayah Abdalla

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ABSTRACT: The current study sheds a light on two fundamental aspects of a transitional separated-reattached flow induced over a two-dimensional blunt flat plate and three-dimensional square cylinder employing large eddy simulation conducted with Open FOAM CFD code. These aspects are different vortices shedding frequency modes and large scale structures and their development. The current paper is the first study to investigate a transitional separated-reattached flow in a three-dimensional square cylinder and compare between transition aspects of this case and that in a two-dimensional flat plate. It is not clear whether all transitional separated-reattached flows have low frequency shear layer flapping and selective high shedding frequency. This issue is addressed. The current LES results show that the characteristic shedding frequency value for the square cylinder is different from that in the flat plate. Coherent structures and their development are visualized at different stages of transition for both geometers. In the square cylinder, Kelvin-Helmholtz rolls are twisting around this geometry and evolve topologically to form hairpin structures. In the flat plate, Kelvin-Helmholtz rolls stay flat and hairpin structures formed by a braking down process

KEYWORDS: Separated-reattached flow, Transition, Shedding frequency modes, Coherent structures, Flow visualization, Large eddy simulation


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WSEAS Transactions on Systems and Control, ISSN / E-ISSN: 1991-8763 / 2224-2856, Volume 12, 2017, Art. #6, pp. 45-72

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