G205 成層乱流中の塩分濃度場と速度場(GS2 乱流の諸問題,一般セッション)

Abstract

Distribution of salinity and velocity in stratified turbulence is investigated by LIF (Laser Induced Fluorescence) and PIV (Particle Image Velocimetry). After the initial development of grid-generated turbulence, the spectrum of salt-concentration field becomes, at small scales, larger than the spectrum of velocity field, since the Schmidt number (=600) of salt is high. However, at larger times, difference between the two spectra diminishes, since the Ozmidov scale becomes smaller than the Kolmogorov scale and the whole velocity spectra are affected by stratification. Then, the significant transform of potential energy (density perturbation) into kinetic energy occurs even at small scales, so that the active scalar such as salt dissipates at the Kolmogorov scale, where the kinetic energy dissipates.