A-341 水銀熱乱流における速度境界層の測定

概要

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We measured the vertical profile of the velocity fluctuation in the experiment of Rayleigh-Benard convection in a low Prandtl number fluid, liquid mercury. This was done in a cell with aspect ratio of 0.5,and using ultrasonic velocimetry. Rayleigh number of (10)^<10> and Reynolds number of (10)^5 were attained in the experiment. We found the inversion of the flow direction near the top plate, which we regard as the emergence of the velocity boundary layer. Furthermore, we observed the macroscopic flow structure consisting of the upward flow in the upper-half region and the downward flow in the lower-half region of the cell, and its occasional vertical movement. Finally, we calculated the energy spectrum E(k) which can be directly compared with Bolgiano-Obukhov theory, without the use of Taylor's frozen-flow hypothesis.
日本流体力学会の論文
2003-07-28