気液乱流界面における局所スカラー束の界面発散に対する依存性(流体工学,流体機械)

概要

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Numerical simulation of a coupled air-water flow and associated interfacial mass transfer is carried out. It is found that the concentration field near the interface responses to the surface divergence quickly even at high Schmidt numbers up to 100. High interfacial scalar flux regious are characterized by spotty structures, which are caused by impingement of the bulk liquid on the interface due to streamwise vortices. In order to clarify quantitative relationship between the local scalar flux and the surface divergence, a one-dimensional advection-diffusion equation is analysed. By introducing two time scales, i. e., renewal and transient time scales, we show that the surface divergence contributes to the mass transfer only when the renewal time scale is larger than the transient time scale and the local scalar flux is analytically calculated from the surface divergence by appling the Chan and Scriven's stagnation flow model. We demonstrate that the above mass transfer model holds fairly well at a wind-driven turbulent interface. This would be a primary reason why a total gas transfer rate is well correlated with the intensity of the surface divergence under a wide variety of flow conditions.
社団法人日本機械学会の論文
2006-05-25