Direct Numerical Simulation of an air-filled differentially heated square cavity with Rayleigh numbers up to 1011
Direct Numerical Simulation of an air-filled differentially heated square cavity with Rayleigh numbers up to 1011
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DOI：
10.1016/j.ijheatmasstransfer.2018.02.042
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发表时间：
2018-08
影响因子：
5.2
通讯作者：
F. Sebilleau;R. Issa;S. Lardeau;S. Walker
中科院分区：
文献类型：
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作者：
F. Sebilleau;R. Issa;S. Lardeau;S. Walker
在瑞利数为10 8 ~ 10 11，普朗特数为0.71的条件下，利用Boussinesq近似在加热方形腔中进行了直接数值模拟。所研究的三维结构代表了一个无限深的空腔，因此对应于一个统计上的二维流动，施加的温度在水平壁上线性变化。在这种构型下，瑞利数和湍流强度是有史以来最高的。本文提出的数据库包括一阶和二阶统计矩、全雷诺应力、湍流热通量和温度方差预算。后者在浮力驱动的流动构型中极为罕见，因此被认为对湍流建模界很有价值。因此，对收集到的数据的分析侧重于与此类流动的雷诺兹平均模型相关的方面。研究了增加瑞利数对流动统计、努塞尔数预测和热分层的影响。研究发现，影响预算行为的最重要方面是温度变化最大值的位置向边界层内部区域的位移。热边界层和速度边界层之间的这种行为差异在预算中引入了负产量区域，这些区域往往随着瑞利数的增加而增加。在所有瑞利数下，浮力产生的湍流也与其他预算项具有相同的数量级。
A set of Direct Numerical Simulations in a heated square cavity invoking the Boussinesq approximation was carried out at Rayleigh numbers ranging between 10 8 and 10 11 and Prandtl number of 0.71. The three dimensional configurations studied represent an infinitely deep cavity, thus corresponding to a statistically two-dimensional flow with an imposed temperature varying linearly on the horizontal walls. In such configuration, the Rayleigh number, and therefore turbulence intensity, is the highest ever reached. The database presented herein includes first and second order statistical moments as well as full Reynolds stresses, turbulent heat fluxes and temperature variance budgets. The latter are extremely rare for buoyancy driven flow configurations and are therefore believed to be valuable to the turbulence modelling community. The analysis of the data collected thus focuses on aspects of relevance to the Reynolds averaged modelling of such flows. The effect of increasing the Rayleigh number on the flow statistics, Nusselt number predictions and thermal stratification is investigated. The most important aspect influencing the behaviour of the budgets was found to be the displacement of the position of the maximum of temperature variance towards the inner zone of the boundary layer. Such difference in behaviour between the thermal and velocity boundary layers introduces regions of negative production in the budgets that tend to increase with the Rayleigh number. The production of turbulence by buoyancy is also found to be of the same order of magnitude as other budget terms at all Rayleigh numbers.