An experimental and computational study of the post-collisional flow induced by an impulsively rotated sphere

Autor:	Benjamin Levy, James P. Denier, Sophie A. W. Calabretto
Rok vydání:	2019
Předmět:	Physics::Fluid Dynamics Boundary layer Jet (fluid) Flow separation Flow (mathematics) Particle image velocimetry Mechanics of Materials Mechanical Engineering Equator Boundary (topology) Mechanics Starting vortex Condensed Matter Physics
Zdroj:	Journal of Fluid Mechanics. 881:772-793
ISSN:	1469-7645 0022-1120
DOI:	10.1017/jfm.2019.783
Popis:	The unsteady flow due to a sphere, immersed in a quiescent fluid, and suddenly rotated, is a paradigm for the development of unsteady boundary layers and their collision. Such a collision arises when the boundary layers on the surface of the sphere are advected towards the equator, where they collide, serving to generate a radial jet. We present the first particle image velocimetry measurements of this collision process, the resulting starting vortex and development of the radial jet. Coupled with new computations, we demonstrate that the post-collision steady flow detaches smoothly from the sphere’s surface, in qualitative agreement with the analysis of Stewartson (Grenzschichtforschung/Boundary Layer Research (ed. H. Görtler), Springer, 1958, pp. 60–70), with no evidence of a recirculation zone, contrary to the conjectured structure of Smith & Duck (Q. J. Mech. Appl. Maths, vol. 20, 1977, pp. 143–156).
Databáze:	OpenAIRE
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