Inam, Mohammad Ilias, Lin, Wenxian, Armfield, Steven W., and He, Yinghe (2014) Asymmetric transition for high froude number plane fountains in linearly stratified fluids. In: Proceedings of the 15th International Heat Transfer Conference. 8812. pp. 1-14. From: IHTC-15: 15th International Heat Transfer Conference, 10-15 August 2014, Kyoto, Japan.

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Abstract

Fountains injected in stratified fluids are widely found in nature and engineering settings. The onset of asymmetry and entrainment that occurs in transitional fountains is the key to shed light on the turbulence generation and entrainment mechanisms in fountains. In addition to the Reynolds number (Re) and the Froude number (Fr), the stratification of the ambient fluid, represented by the dimensionless temperature stratification parameter (s), will also have a significant effect on the onset of asymmetry, unsteadiness, and entrainment in fountains. In this study, a series of direct numerical simulation were carried out using ANSYS Fluent for transitional plane fountains in linearly-stratified fluids with Re and s in the ranges 25 ≤ Re ≤ 300 and 0.1 ≤ s ≤ 0.5, all at Fr = 10. The results show many features of the transient behaviour of the fountains, in particular the effects of Re and s on the asymmetric behaviour and the time for the onset of asymmetry and unsteadiness. It is found that these fountains generally maintain symmetry in the early developing stage, but become asymmetric and unsteady after that. However, the results also show that the stratification of the ambient fluid tends to stabilize and alleviate the asymmetry and unsteadiness of the fountain flows and its effect on the asymmetric behaviour of the fountains is weaker than that of Re. The results further demonstrate that the asymmetric behaviour of a plane fountain can be represented and quantified by the maximum values of U and V at X = 0 in the Y-Z plane, respectively, where U and V are the velocity components in the X and Y directions and Z is the vertical direction in which the fountain is ejected and the negative buoyancy is experienced by it, as any non-zero U or V will indicate the asymmetric behaviour in the X or Y direction on the plane. Empirical correlations were developed for the fountains using the obtained numerical results to quantify the effects of Re and s on the times for the onset of the asymmetric behaviour of plane fountains both in the X direction and in the Y direction.

Item ID:	37286
Item Type:	Conference Item (Research - E1)
ISBN:	978-1-56700-421-2
Keywords:	numerical simulation and super-computing, computational methods, direct numerical simulation, transitional plane fountain, asymmetry, entrainment, unsteady flow, stratification
Related URLs:	Organisation Publisher
Funders:	National Natural Science Foundation of China, Yunnan Natural Science Foundation, China, Australian Research Council (ARC)
Projects and Grants:	National Natural Science Foundation of China (11072211), Yunnan Natural Science Foundation (2011FA017)
Date Deposited:	17 Feb 2015 02:26
FoR Codes:	09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 100%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 100%
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