Kunnen R P J, Clercx H J H, Geurts B J
Fluid Dynamics Laboratory, Department of Physics, International Collaboration for Turbulence Research (ICTR) and J. M. Burgers Center for Fluid Dynamics, Eindhoven University of Technology, Eindhoven, The Netherlands.
Phys Rev Lett. 2008 Oct 24;101(17):174501. doi: 10.1103/PhysRevLett.101.174501. Epub 2008 Oct 20.
In this Letter we report experimental evidence that rotation enhances vertical inhomogeneity in turbulent convection, in spite of the increased columnar flow ordering under rotation. Measurements using stereoscopic particle image velocimetry have been carried out on turbulent rotating convection in water. At constant Rayleigh number Ra=1.11 x 10(9) several rotation rates have been used, so that the Rossby number takes values from Ro=infinity (no rotation) to 0.09 (strong rotation). The three-component velocity data, obtained at two vertical positions, are used to investigate the anisotropy of the flow through the invariants of the Reynolds-stress anisotropy tensor and the Lumley triangle, as well as to correlate the vertical velocity and vorticity. In the center plane rotation causes the turbulence to be "rodlike," while closer to the top plate a trend toward isotropy is observed.
在本信函中，我们报告了实验证据，即尽管旋转会使柱状流的有序性增强，但它仍会加剧湍流对流中的垂直不均匀性。我们利用立体粒子图像测速技术对水中的湍流旋转对流进行了测量。在瑞利数Ra = 1.11×10⁹保持恒定的情况下，我们采用了几种不同的旋转速率，使得罗斯比数取值范围从Ro = ∞（无旋转）到0.09（强旋转）。在两个垂直位置获取的三分量速度数据，被用于通过雷诺应力各向异性张量的不变量和拉姆利三角形来研究流动的各向异性，以及关联垂直速度和涡度。在中心平面，旋转使湍流呈“棒状”，而在靠近顶板处则观察到一种趋向各向同性的趋势。
