| Scaling of maximum probability density function of velocity increments in turbulent Rayleigh-Bénard convection |
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| 摘 要： | In this paper, we apply a scaling analysis of the maximum of the probability density function(pdf) of velocity increments, i.e., max() = max()up p u, for a velocity field of turbulent Rayleigh-Bénard convection obtained at the Taylor-microscale Reynolds number Re60. The scaling exponent is comparable with that of the first-order velocity structure function, (1), in which the large-scale effect might be constrained, showing the background fluctuations of the velocity field. It is found that the integral time T(x/ D) scales as T(x/ D)(x/ D), with a scaling exponent =0.25 0.01, suggesting the large-scale inhomogeneity of the flow. Moreover, the pdf scaling exponent (x, z) is strongly inhomogeneous in the x(horizontal) direction. The vertical-direction-averaged pdf scaling exponent (x) obeys a logarithm law with respect to x, the distance from the cell sidewall, with a scaling exponent 0.22 within the velocity boundary layer and 0.28 near the cell sidewall. In the cell's central region, (x, z) fluctuates around 0.37, which agrees well with (1) obtained in high-Reynolds-number turbulent flows, implying the same intermittent correction. Moreover, the length of the inertial range represented in decade()IT x is found to be linearly increasing with the wall distance x with an exponent 0.65 0.05.
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| 收稿时间： | 31 March 2014 |
Scaling of maximum probability density function of velocity increments in turbulent Rayleigh-Bénard convection |
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| Affiliation: | 1. School of Science, Shanghai Institute of Technology, Shanghai 200235, China;2. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China;3. Physics of Fluids Group, University of Twente, AE Enschede, The Netherlands;1. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China;2. Hydraulic Structures design division, Hydrochina Huadong Engineering Corporation, Hangzhou 310014, China;1. Forschungszentrum Küste, Leibniz Universität Hannover, Hannover, Germany;2. Department of Marine Technology, Norwegian University of Science and Technology, Trondheim, Norway;1. School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore;2. Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China;3. School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore;1. Department of Applied Mechanics and Engineering, Sun Yat-sen University, Guangzhou 510275, China;2. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China;3. Department of Applied Mechanics and Engineering, Sun Yat-sen University, Guangzhou 510275, China |
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| Abstract: | |
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| Keywords: | Rayleigh-Bénard convection scaling probability density function (pdf) |
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