J056023 強い温度安定成層を伴う乱流境界層の乱流構造解析([J05602]乱流における運動量,熱,物質の輸送現象(2))

概要

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In order to explore and investigate turbulent structures and statistics of turbulent boundary layer under strong stable stratification, direct numerical simulation (DNS) is carried out. The DNS results show the quantitative turbulent statistics of strong stable thermal boundary layer in detail. In particular, the counter gradient diffusion phenomenon is found in a strong, stable stratified boundary layer (SSBL) in both velocity and thermal fields, i.e., Reynolds shear stress and the wall-normal turbulent heat-flux indicate a reverse sign as compared with those of the neutral boundary layer, though the positive gradients of mean velocity and temperature are maintained. On the other hand, since the friction velocity of SSBL becomes remarkably small due to decrease in turbulence near the wall, the space of calculation normalized by wall unit becomes narrow. It is, however, unearthed that the calculation region does not influence the results. Also, the characteristics turbulent structures of boundary layer under strong stable stratification are revealed, where the vortex structure vanishes obviously at the downstream region.
一般社団法人日本機械学会の論文
2011-09-11