安定および不安定成層を形成する格子乱流場における速度とスカラのクロススペクトルについて(成層(2),一般講演)

概要

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The effects of stable and unstable thermal stratifications on the cross spectra between passive scalar (dye concentration) fluctuation c and vertical velocity fluctuation υ in shear-free grid turbulence are investigated using previously published data. The results show that cospectra in the neutral stratification have a slope close to -7/3, as predicted by Lumley (1964). In the moderately stable stratification, the scaling laws of the cospectrum and coherence collapse in the downstream region. However, in the strongly stable stratification, the cospectrum in the countergradient region reconstructs a small but distinct region close to -7/3 after the collapse. In the unstable stratification, despite strong convective motions, the cospectra exhibit -7/3 power decay regions.
日本流体力学会の論文
2008-09-04