Heat transport properties of plates with smooth and rough surfaces in turbulent thermal convection
Heat transport properties of plates with smooth and rough surfaces in turbulent thermal convection
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DOI：
10.1017/jfm.2013.638
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发表时间：
2014-01
影响因子：
3.7
通讯作者：
Ping Wei;T. Chan;R. Ni;Xiao-Zheng Zhao;K. Xia
中科院分区：
文献类型：
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作者：
Ping Wei;T. Chan;R. Ni;Xiao-Zheng Zhao;K. Xia
摘要本文对光滑和粗糙两种不同组合形式的湍流热对流进行了实验研究。实验共使用了5个细胞。测量每个板（或相关边界层）的全局$\mathit{Nu}$和$\mathit{Nu}$。结果表明，光滑板对同一单元的另一个板的表面（粗糙或光滑）和边界条件（即名义上的恒定温度或恒定通量）不敏感。另一方面，粗板的传热特性不仅取决于单元另一侧板的性质，而且还取决于该板的边界条件。由此看来，在目前的实验分辨率水平上，光滑板可以影响粗糙板，但不受粗糙板或光滑板的影响。进一步发现，对于所有光滑板，$\mathit{Nu}$与$\mathit{Ra}$的标度符合经典的$1/ 3$指数。但是，对于两个板都光滑的单元，全局$\mathit{Nu}$的缩放指数肯定小于$1/ 3$（这个结果本身与之前在可比参数范围内的所有研究一致）。$\mathit{Nu}$行为在整个细胞和单个培养皿水平之间的差异尚不清楚，值得进一步研究。
Abstract We present an experimental study of turbulent thermal convection with smooth and rough surface plates in various combinations. A total of five cells were used in the experiments. Both the global $\mathit{Nu}$ and the $\mathit{Nu}$ for each plate (or the associated boundary layer) are measured. The results reveal that the smooth plates are insensitive to the surface (rough or smooth) and boundary conditions (i.e. nominally constant temperature or constant flux) of the other plate of the same cell. The heat transport properties of the rough plates, on the other hand, depend not only on the nature of the plate at the opposite side of the cell, but also on the boundary condition of that plate. It thus appears that, at the present level of experimental resolution, the smooth plate can influence the rough plate, but cannot be influenced by either the rough or the smooth plates. It is further found that the scaling of $\mathit{Nu}$ with $\mathit{Ra}$ for all of the smooth plates is consistent with the classical $1/ 3$ exponent. But the scaling exponent for the global $\mathit{Nu}$ for the cell with both plates being smooth is definitely less than $1/ 3$ (this result itself is consistent with all previous studies at comparable parameter range). The discrepancy between the $\mathit{Nu}$ behaviour at the whole-cell and individual-plate levels is not understood and deserves further investigation.