摘要: |
采用二维流体力学基本方程组对普朗特数Pr=0.72的具有水平流动的底部加热两板之间的流动特性进行数值模拟。结果表明,对于给定相对瑞利数r,随着雷诺数Re的增加,底部加热的两板之间依次出现定常对流滚动,均匀行波对流滚动,具有水平流动进口段的局部行波对流滚动及水平流动。对于相对瑞利数r=3,在雷诺数9.0
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关键词: 水平流动 对流滚动 进口段长度 局部行波 |
DOI:10.12170/201904008 |
分类号:O357 |
基金项目:国家自然科学基金资助项目(10872164); 西北旱区生态水利国家重点实验室基金项目(2017ZZKT-2) |
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Analysis of entrance region of horizontal flow between two plates heated from bottom |
NING Lizhong1, ZHANG Ke1, NING Bibo2, HU Biao3, TIAN Weili4
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1.State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China (Xi’an University of Technology), Xi’an;2.College of Civil Engineering and Architecture, Jiaxing University, Jiaxing;3.Jiangxi Provincial Design & Research Institute of Water Conservancy & Hydropower, Nanchang;4.Department of Architecture, Shanghai University, Shanghai
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Abstract: |
The two-dimensional basic equations of fluid mechanics are used to numerically simulate the characteristics of flow between two plates heated from below with horizontal flows, with the Prandtl number Pr equaling 0.72. The numerical simulation results show that for a given reduced Rayleigh number r, with the increase of the Reynolds number Re, there appear steady convective rolls, uniform traveling wave convective rolls, localized traveling wave convective rolls with the entrance region of the horizontal flow, and the horizontal flows occur successively between two plates heated from the bottom. When the Reynolds number Re is between 9.0 and 21.0 and the reduced Rayleigh number r equals 3, the localized traveling wave convection rolls occur in the system and there exists the entrance region of the horizontal flow. The length of the entrance region of the horizontal flow X0 increases with the increase of the Reynolds number. When the reduced Rayleigh number r is between 4 and 12, and the Reynolds number Re equals 25.0, the localized traveling wave convection rolls occur between two plates and there exists the entrance region of the horizontal flow. The length of the entrance region of the horizontal flow decreases with the increase of the reduced Rayleigh number. And finally, the empirical formulas for the length X0of the entrance region varying with the Reynolds number or the reduced Rayleigh number are given in this paper. |
Key words: horizontal flow convection rolls entrance region length localized traveling wave |