C-232 地表面の周期的温度変化を伴うエックマン乱流境界層の DNS

概要

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The direct numerical simulations (DNS) of the turbulent Ekman layer with a periodical temperature variation on a smooth ground surface are performed using the Boussinesq approximation to account for the buoyancy effect. The Reynolds number based on the geostrophic wind G. the Ekman layer depth D and the kinematic viscosity ν is 410. The Grashof number is set to be Gr. 0 (non-buoyancy), and 3.15 × 10^7 (with buoyancy) in order to examine an effect of the stratification. The condition of the stratification is changed by a periodical variation of the ground temperature. In this layer, three-dimensional velocity profile is observed. So the stratification has a great influence on the flow direction in the vicinity of the ground. Turbulence quantities are phase-averaged to investigate the stable and unstable stratifications upon them. Instantaneous flow field is visualized. The suppression, and enhancement of turbulence are observed in the stable and unstable periods, respectively.
日本流体力学会の論文
2003-07-28