Asymmetry and penetration of transitional plane fountains in stratified fluid
Asymmetry and penetration of transitional plane fountains in stratified fluid
复制标题
分层流体中过渡平面喷泉的不对称性和穿透性
DOI：
10.1016/j.ijheatmasstransfer.2015.07.062
复制
发表时间：
2015-11
影响因子：
5.2
通讯作者：
Yinghe He
中科院分区：
文献类型：
--
作者：
Mohammad Ilias Inam;林文贤;S.W. Armfield;Yinghe He
注入分层流体的喷泉广泛应用于环境和工业环境中。过渡喷泉中发生的不对称和夹带的开始是理解喷泉中湍流产生和夹带机制的关键。除了雷诺数 (Re) 和弗劳德数 (Fr) 之外，由无量纲温度分层参数 (s) 表示的环境流体的分层也对喷泉中不对称、不稳定和夹带的发生以及喷泉在环境流体中渗透的最大高度有显着影响。在本研究中，使用 ANSYS Fluent 对 Re 和 s 范围为 25⩽ Re⩽ 300 和 0⩽ s⩽ 0.5 且 Fr= 10 的线性分层流体中的过渡平面喷泉进行了一系列三维直接数值模拟 (DNS)。喷泉的瞬态行为，特别是 Re 和 s 对不对称过渡和最大喷泉渗透的影响高度，使用 DNS 结果进行分析和量化。研究发现，喷泉在发展初期一般是对称的，但随后就变得不对称且不稳定。环境流体的分层被证明可以稳定喷泉流并减少其不对称性和不稳定性。然而，s 对喷泉不对称行为的影响被发现弱于 Re。使用数值结果开发了经验相关性，以量化对不对称转变时间的影响。还分析了 Re 和 s 对初始和时间平均最大喷泉高度（分别为 z m, i 和 z m, a）以及达到 z m, i 的时间的影响。使用 DNS 结果开发了量化相关性，这表明 z m、i 和 z m 都随着 Re 的增加而增加，但随着 s 的增加而减少，这显然是由于喷泉必须克服以穿透周围流体的负浮力的增加。结果进一步表明，s对z m，i和z m，a的影响远强于Re。
Fountains injected into stratified fluids are widely found in environmental and industrial settings. The onset of asymmetry and entrainment that occurs in transitional fountains is the key to understanding 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), also has a significant effect on the onset of asymmetry, unsteadiness, and entrainment in a fountain, and on the maximum height that the fountain penetrates in the ambient fluid. In this study, a series of three-dimensional direct numerical simulations (DNS) were carried out using ANSYS Fluent for transitional plane fountains in linearly-stratified fluids with Re and s in the ranges of 25⩽ Re⩽ 300 and 0⩽ s⩽ 0.5, all at Fr= 10. The transient behavior of the fountains, in particular the effects of Re and s on the asymmetric transition and the maximum fountain penetration heights, is analysed and quantified using the DNS results. It is found that fountains are generally symmetric in the early developing stage, but become asymmetric and unsteady subsequently. The stratification of the ambient fluid is shown to stabilize the fountain flow and to reduce its asymmetry and unsteadiness. However, the effect of s on the asymmetric behavior of a fountain is found to be weaker than that of Re. Empirical correlations were developed, using the numerical results, to quantify such effects on the time for the asymmetric transition. The effects of Re and s on the initial and time-averaged maximum fountain heights (z m, i and z m, a, respectively), and the time to attain z m, i are also analysed. Quantified correlations are developed using the DNS results, which demonstrate that both z m, i and z m, a increase with Re, but decrease with s, apparently due to the increasing negative buoyancy that the fountain must overcome to penetrate the ambient fluid. The results further show that the effect of s on z m, i and z m, a is much stronger than that of Re.
登录
查看更多内容
DOI：
10.1017/s0022112099006953
发表时间：
2000-01
期刊：
J.Fluid Mech.
影响因子：
--
作者：
Wenxian Lin;S.W.Armfield
通讯作者：
S.W.Armfield
均匀流体中层流平面喷泉的高度和稳定性
DOI：
10.1016/j.ijheatmasstransfer.2008.02.022
发表时间：
2008-09
影响因子：
5.2
作者：
G. D. McBain;N. Srinarayana;林文贤;S. W. Armfield
通讯作者：
S. W. Armfield
影响因子：
3.7
作者：
O. J. Myrtroeen;G. Hunt
通讯作者：
O. J. Myrtroeen;G. Hunt
影响因子：
2
作者：
W. Lin;S. Armfield
通讯作者：
W. Lin;S. Armfield
DOI：
10.1016/j.ijheatmasstransfer.2008.02.047
发表时间：
2008-10
影响因子：
5.2
作者：
Wenxian Lin;S. Armfield
通讯作者：
Wenxian Lin;S. Armfield