| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
The simultaneous measurements of temperature and velocity in a turbulent Rayleigh-Bernard convection at high Rayleigh number were carried out using the liquid crystal thermometry in combination with the particle image velocimetry. These measurements allow for the evaluation of statistical properties of turbulence and the knowledge of coherent structure with respect to the heat transfer characteristics. In addition to the measurement of mean flow and turbulence characteristics, the temperature fluctuation, turbulent heat flux and dissipation rate are measured simultaneously. Thus, the balances of turbulence energy and temperature fluctuation are evaluated from the measurements. It is found that the production of turbulence energy is balanced by the dissipation rate in the convection layer, and they increases as the wall is approached. On the other hand, the production of temperature fluctuation, the dissipation rate, the diffusion and the convection are all small and they are in balance in the convection layer, while the production and dissipation rate grows near the wall due to the presence of temperature gradient.
The development of the plume structure is visualized by the three-dimensional simultaneous measurement of temperature and velocity by scanning light sheet technique in combination with the stereo simultaneous measurement of temperature and velocity in the thermal convection. It is found that the temperature contour and the velocity contour shows a similar structure in the convection layer, suggesting the influence of velocity field on the development of the plume. On the other hand, the relationship between the plume and the spoke structure near the wall was examined by the simultaneous multi-plane measurement of temperature and velocity by liquid crystals. The results show that the growth of the spoke structure leads to the formation of plume and the following development of plume structure.
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