Characterisation of Low Reynolds Number Fountain Behaviour
Williamson, N., Srinarayana, N., Armfield, S.W., McBain, G., and Lin, W. (2007) Characterisation of Low Reynolds Number Fountain Behaviour. Proceedings of the Sixteenth Australasian Fluid Mechanics Conference. 16th Australasian Fluid Mechanics Conference , 3-7 December 2007, Gold Coast, Australia , pp. 699-703.
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Experimental evidence for previously unreported fountain behaviouris presented. It has been found that the first unstable mode of a wall bounded three dimensional round fountain is a laminar flapping motion that can grow to a circling or multi-modal flapping motion. With increasing Froude and Reynolds numbers, fountain behaviour becomes more disorderly,exhibiting a laminar bobbing motion. The transition between steady behaviour, the initial flapping modes and the laminar bobbing flow can be approximately described by a function C = FrRe2/3. The transition to turbulence occurs at Re > 120, independent of Froude number. For Fr > 20 and Re . 120, sinuous shear instabilities have been observed in the rising fluid column. For Re > 120 these instabilities cause the fountain to intermittently breakdown into turbulent jet like flow. A regime map of the fountain behaviour for 0:7 < Fr < 55 and 15 < Re < 1100 is presented and the underlying mechanisms for the observed behaviour are proposed.
|Item Type:||Conference Item (Refereed Research Paper - E1)|
|Keywords:||fountain; experimental study; instability; entrainment; transitional flow; buoyancy|
|FoR Codes:||09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 100%|
|SEO Codes:||97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 50%|
97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 50%
|Deposited On:||31 Jul 2009 14:06|
|Last Modified:||24 Nov 2011 08:57|
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