A121 平均せん断のない気液界面下の乱流構造と乱流スカラー輸送(A-12 環境流体(2),一般講演)

概要

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This study focuses on turbulence structures and turbulent passive scalar transfer into a shear-free turbulent liquid across a gas-liquid interface. A direct numerical simulation (DNS) technique is employed to develop an initially homogeneous and isotropic turbulence by inserting two shear-free boundaries in one direction at some specific time. Hence, isotropy of turbulence is destroyed, in particular in the region next to the interface, due to the blocking effect of the interface. We take a closer look into the velocity and scalar fluctuations under the interface. It is found that the surface divergence, S, which has a dimension of inverse of time, will be one of the suitable indicator to quantify activity of surface-renewal at the interface, because the instantaneous scalar gradient at the interface decays exponentially, propotional to the inverse square of S. This result indicates that S could be used as characteristic time scale for evaluation of turbulent scalar transfer rate,
日本流体力学会の論文
2004-08-09