F125 回転成層乱流における鉛直渦の生成, 発達機構に及ぼす力学的パラメータの効果

概要

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In the Earth's atmosphere, zonal currents with a vertical velocity gradient are induced under the action of rotation and horizontal temperature gradient. In these currents, the vertical velocity gradient and horizontal temperature gradient must satisfy the thermal wind equation. In this study, the generation and development mechanisms of vertical vortices are investigated by using direct numerical simulation of homogeneous shear flow where the mean flow satisfies the thermal wind equation. The stable density stratification is also imposed in the vertical direction. The effects of the Coriolis force, buoyancy and Reynolds number are studied in detail. As a result, stable stratification is found to determine the time development of the vertical vorticity. Especially, it is found that when the stable stratification is not intense, the vertical vorticity increases and the cyclones become dominant in comparison to anticyclones, which indicates the combined effects of Coriolis force and nonlinear term. On the other hand, in the cases of strong stable stratification, the vertical vorticity decreases and the effect of the nonlinear term is not so clearly observed.
日本流体力学会の論文
2000-07-25