A numerical simulation of the flow development behind a circular cylinder started from rest and a criterion for investigating unsteady separating flows |
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Authors: | Dr Y C Sun Prof S F Shen Prof Z Zhu |
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Affiliation: | (1) Institute for Theoretical Fluid Mechanics, DFVLR-AVA, Bunsenstrasse 10, D-3400 Göttingen, Federal Republic of Germany;(2) Sibley School of Mechanical and Aerospace Engineering, Cornell University, 14853 Ithaca, New York, USA;(3) Beijing Institute of Aeronautics and Astronautics, Beijing, China |
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Abstract: | Summary The numerical solution of the Navier-Stokes equations for an unsteady compressible flow is employed to follow the development of periodic vortex shedding behind a circular cylinder starded from rest. The periodic vortex shedding is found to be a direct consequence of the interaction between the upper and lower primary vortices behind the cylinder, while the topological instability of the full saddle-point joining the vortices and the outer flow can be seen to play a predominant role in the process. A criterion based upon the rate of distortion of fluid elements and derived from the previous Lagrangian analysis of boundary-layer separation has been applied to the present study of unsteady separating flow and is found to be instrumental in revealing critical regions and surfaces in the flow where the fluid elements are extremely deformed.With 12 FiguresAt DFVLR-Institute for Theoretical Fluid Mechanics on Alexander-von-Humboldt Senior-Scientist Award.At DFVLR-Institute for Theoretical Fluid Mechanics on leave from Beijing Institute of Aeronautics and Astronautics. |
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