Global instabilities in diverging channel flows

Swaminathan, G and Sahu, K C and Sameen, A and Govindarajan, R (2011) Global instabilities in diverging channel flows. Theoretical and Computational Fluid Dynamics, 25 (1-4). pp. 53-64. ISSN 0935-4964

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A global stability study of a divergent channel flow reveals features not obtained hitherto by making either the parallel or the weakly non-parallel (WNP) flow assumption. A divergent channel flow is chosen for this study since it is the simplest spatially developing flow: the Reynolds number is constant downstream, and for a theoretical Jeffery-Hamel flow, the velocity profile obeys similarity. Even in this simple flow, the global modes are shown to be qualitatively different from the parallel or WNP. In particular, the disturbance modes are often not wave-like, and the local scale, estimated from a wavelet analysis, can be a function of both streamwise and normal coordinates. The streamwise variation of the scales is often very different from the expected linear variation. Given recent global stability studies on boundary layers, such spatially extended modes which are not wave-like are unexpected. A scaling argument for why the critical Reynolds number is so sensitive to divergence is offered.

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Item Type: Article
Uncontrolled Keywords: Critical Reynolds number; Developing Flow; Divergent channel; Diverging channel; Global instability; Global stability; Global stability analysis; Jeffery-Hamel flows; Linear variation; Local scale; Normal coordinate; Streamwise variations; Velocity profiles
Subjects: Chemical Engineering > Biochemical Engineering
Others > Mechanics
Divisions: Department of Chemical Engineering
Depositing User: Team Library
Date Deposited: 31 Oct 2014 10:06
Last Modified: 09 Mar 2015 10:45
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