大規模乱流中で蛇行運動する熱プルームの絶対・相対拡散の特性(拡散・熱物質輸送(2),一般講演)

概要

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Thermal diffusion of a heated plume from a point source was experimentally investigated in homogeneous quasi-isotropic and uniform shear flow turbulence fields. For R_λ=360〜520, Taylor's short-time diffusion was clearly observed, accompanying plume's meandering motion. The effect of meandering motion and the characteristics of the relative dispersion inside the plume were quantitatively extracted through time averaged and conditional sampling analysis. In the region of the short-time diffusion, relative dispersion was actively conducted by medium and small scale turbulent eddies in the meandering plume. As the diffusion field shifts into the long-time diffusion, the plume width grows larger than the large scale turbulent eddies and the inertial subrange of thermal fluctuation spectrum becomes expanded towards the lower wave number range apparently having the gradient of -5/3.
日本流体力学会の論文
2008-09-04