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Vortex rings impinging on permeable boundaries


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Authors

Mujal-Colilles, A 
Dalziel, SB 
Bateman, A 

Abstract

jats:pExperiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring impinging four different reticulated foams (with permeability k ∼ 26 − 85 × 10−8 m2) and a solid boundary. Results show how permeability affects the stretching phenomena of the vortex ring and the formation and evolution of the secondary vortex ring with opposite sign. Moreover, permeability also affects the macroscopic no-slip boundary condition found on the solid boundary, turning it into an apparent slip boundary condition for the most permeable boundary. The apparent slip-boundary condition and the flux exchange between the ambient fluid and the foam are jointly responsible for both the modified formation of the secondary vortex and changes on the vortex ring diameter increase.</jats:p>

Description

Keywords

Vortex rings, Foams, Rotating flows, Boundary value problems, Velocimetry

Journal Title

Physics of Fluids

Conference Name

Journal ISSN

1070-6631
1089-7666

Volume Title

27

Publisher

AIP Publishing
Sponsorship
The experimental work presented herein was conducted during a four-months-long visit of A.M.C. to the Department of Applied Mathematics and Theoretical Physics at Cambridge University, UK. The financial support of the Ministerio de Educacion y Ciencia de España through Grant No. CGL 2009-13039 is gratefully acknowledged. The support of the UPC-Barcelona Tech University is also acknowledged.