Vortex-Induced Vibration of a Neutrally Buoyant Tethered Sphere

Lee, H, Thompson, M. C and Hourigan, K. (2007). Vortex-Induced Vibration of a Neutrally Buoyant Tethered Sphere. In: Peter Jacobs, Tim McIntyre, Matthew Cleary, David Buttsworth, David Mee, Rose Clements, Richard Morgan and Charles Lemckert, 16th Australasian Fluid Mechanics Conference (AFMC). 16th Australasian Fluid Mechanics Conference (AFMC), Gold Coast, Queensland, Australia, (580-585). 3-7 December, 2007.

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Author Lee, H
Thompson, M. C
Hourigan, K.
Title of paper Vortex-Induced Vibration of a Neutrally Buoyant Tethered Sphere
Conference name 16th Australasian Fluid Mechanics Conference (AFMC)
Conference location Gold Coast, Queensland, Australia
Conference dates 3-7 December, 2007
Proceedings title 16th Australasian Fluid Mechanics Conference (AFMC)
Place of Publication Brisbane, Australia
Publisher School of Engineering, The University of Queensland
Publication Year 2007
Year available 2007
Sub-type Fully published paper
ISBN 978-1-864998-94-8
Editor Peter Jacobs
Tim McIntyre
Matthew Cleary
David Buttsworth
David Mee
Rose Clements
Richard Morgan
Charles Lemckert
Start page 580
End page 585
Total pages 6
Collection year 2007
Language eng
Abstract/Summary Recent preliminary experiments have indicated that a neutrally buoyant tethered sphere develops a large diameter quasi-circular trajectory, unlike the oscillations observed for non-neutrally buoyant tethered spheres. This shows similarities to the path of buoyant bubbles, which may follow zig-zag and/or helical paths depending on the Reynolds number. The current study explores the behaviour using well resolved numerical simulations. The forces like tension, buoyancy and fluid force are considered. It is found that there exist six different flow regimes within the range of the Reynolds number = [50, 800] according to the sphere response. Regime I (Re = [50, 205]) and Regime II (Re = [210, 260]) are characterised by steady axisymmetric flow structure without body movement except the loss of axisymmetry in Regime II. The sphere starts to vibrate from Regime III (Re = [270, 280]). Regime IV (Re = [300, 330]) shows suppressed body oscillation and steep decrease of off-centered distance in the plane normal to streamwise direction (yz plane). In Regime V (Re = [335, 550]), the sphere oscillates around (0, 0) in yz plane. The sphere of Regime VI (Re = [600, 800]) oscillates rather irregularily. The transitions are compared with those for a fixed sphere. In addition, the effect of moving away from neutral buoyancy is examined.
Subjects 290501 Mechanical Engineering
Q-Index Code E1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Conference Paper
Collection: 16th Australasian Fluid Mechanics Conference
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Created: Wed, 19 Dec 2007, 12:55:21 EST by Laura McTaggart on behalf of School of Engineering