Direct Simulation Of Fountains With Intermediate Froude And Reynolds Numbers
Direct Simulation Of Fountains With Intermediate Froude And Reynolds Numbers
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DOI：
10.21914/anziamj.v45i0.873
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发表时间：
2004-02
期刊：
影响因子：
0.9
通讯作者：
Wenxian Lin;S. Armfield
中科院分区：
文献类型：
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作者：
Wenxian Lin;S. Armfield
具有中间弗劳德数和雷诺数的喷泉具有根本意义，特别是对于理解湍流喷泉中的湍流和夹带机制。然而，对这些过渡喷泉的行为进行研究的工作却很少。本文通过直接数值模拟研究了1?Fr?8 和200?Re?800 轴对称喷泉的瞬态行为。研究发现，当Re≤200时，即使Fr高达8，喷泉的下流与环境之间也几乎没有混合；然而，当Re≥400时，喷泉下降流与环境之间的混合变得更强，这表明夹带和湍流主要是由Re引起的，而Fr的贡献要小得多；即使当流动达到准稳态时，由于下降流和底部边界之间的相互作用和/或下降流和环境之间的夹带，最大喷泉穿透高度 z m 也会波动；对于1≤Fr≤8 和100≤Re≤800，平均z m 与FrRe 1/4 成比例。
Fountains with intermediate Froude and Reynolds numbers are of fundamental interest, especially for understanding the mechanism of turbulence and entrainment in turbulent fountains. However there has been little work done to investigate the behavior of these transitional fountains. In this work, the transient behavior of axisymmetric fountains with 1?Fr?8 and 200?Re?800 is studied by direct numerical simulation. It is found that when Re?200, there is little mixing between the downflow of the fountain and the ambient, even for Fr as high as 8; however, when Re?400, the mixing between the fountain downflow and the ambient becomes stronger, indicating that the entrainment and the turbulence are mainly due to Re and the contribution from Fr is much smaller; The maximum fountain penetration height z m fluctuates, even when the flow reaches the quasi-steady state, due to the interaction between the downflow and the bottom boundary and/or the entrainment between the downflow and the ambient; The averaged z m scales with FrRe 1/4 for 1?Fr?8 and 100?Re?800.