du Puits Ronald, Resagk Christian, Thess André
Ilmenau University of Technology, Department of Mechanical Engineering, P.O. Box 100565, 98684 Ilmenau, Germany.
Phys Rev Lett. 2007 Dec 7;99(23):234504. doi: 10.1103/PhysRevLett.99.234504. Epub 2007 Dec 6.
In this Letter, highly resolved measurements of the horizontal velocity inside the boundary layer of turbulent Rayleigh-Bénard convection are reported. They were performed in a cylindrical box with an aspect ratio Gamma=1.13 which was filled with air with a Prandtl number Pr=0.7. The horizontal velocity was measured along the central axis close to the cooling plate in a range of Rayleigh numbers between Ra=10;{11} and Ra=10;{12} using a two-dimensional laser Doppler velocimeter. We demonstrate that the profile of the mean velocity strongly differs from that of classical shear flows like the Blasius shape of a laminar flat plate boundary layer or a turbulent logarithmic velocity profile with standard coefficients.
在本信函中，报告了对湍流瑞利-贝纳德对流边界层内水平速度的高分辨率测量结果。这些测量是在一个长宽比Γ = 1.13的圆柱形盒子中进行的，盒子里充满了普朗特数Pr = 0.7的空气。使用二维激光多普勒测速仪，在瑞利数介于Ra = 10¹¹和Ra = 10¹²之间的范围内，沿着靠近冷却板的中心轴测量水平速度。我们证明，平均速度的剖面与经典剪切流的剖面有很大不同，比如层流平板边界层的布拉修斯形状或具有标准系数的湍流对数速度剖面。
