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Scalar Transfer Mechanisms at the Sheared Air-Water Interface : Estimation of Scalar Transfer Rate

剪切空气-水界面处的标量传递机制：标量传递率的估计

基本信息

批准号：
14102016
负责人：
KOMORI Satoru
金额：
$ 64.81万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (S)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2006
项目状态：
已结题

项目摘要

It is of great importance to investigate scalar (heat and mass) transfer mechanism across the air-sea interface in order to improve the reliability of predictions for global warming. However, previous sub-models used in a general circulation model for predicting heat and mass transfer velocities across the air-sea interface have been based on the simple assumption that the transfer velocities are proportional to wind velocity over the ocean surface. This rough assumption reduces the reliability of the sub-models. The aim of this study is, therefore, to clarify the scalar transfer mechanism across the sheared air-water interface from the fluid-mechanical point of view and to develop reliable models for the scalar transfer velocity that truly reflects the physical processes involved.The effects of wind speed, fetch, swell, surface contamination, thermal stratification, entrained bubbles, dispersing droplets and rainfall on the mass transfer across the air-water interface have been invest … More igated by carrying out both laboratory experiments and numerical simulation. The results show that the mass transfer velocity k_L, is not simply proportional to the wind speed and it has a kink in the middle wind speed region. The mass transfer velocity is well correlated with the frequency of the appearance of the surface-renewal eddies, since the mass transfer across the sheared air-water interface is controlled by the surface-renewal eddies. The effect of fetch on k_L is compensated when the free-stream wind speed is used as a wind parameter. Both swell and surface contaminants reduce the mass transfer but the thermal stratification in the water flow does not affect the mass transfer because of strong wind-driven turbulence. The entrained bubbles due to intense wave breaking in the high wind speed region significantly promote the mass transfer but the effect of dispersing droplets is negligibly small. The rainfall enhances the mass transfer across the air-water interface and the promotion effect is well described by the momentum flux of rainfall. The details of the results should be refereed to our published articles. Less

研究海-气界面标量（热量和质量）传输机制对提高全球变暖预测的可靠性具有重要意义。然而，以前的子模式中使用的一般环流模式，用于预测跨越空气-海洋界面的热量和质量转移速度的基础上的简单假设，即转移速度是成比例的风速在海洋表面。这种粗略的假设降低了子模型的可靠性。因此，本研究的目的是从流体力学的角度阐明剪切空气-水界面上的标量传输机制，并建立真实反映所涉及的物理过程的标量传输速度的可靠模型。研究了分散液滴和降雨对气-水界面传质的影响 ...更多信息通过实验室试验和数值模拟相结合，结果表明，传质速度kL与风速不是简单的正比关系，在中等风速区存在拐点。传质速度与表面更新涡的出现频率有很好的相关性，因为剪切空气-水界面的传质是由表面更新涡控制的。采用自由流风速作为风场参数，补偿了风场对k_L的影响。膨胀和表面污染物都降低了传质，但水流中的热分层并不影响传质，因为强烈的风力驱动的湍流。在高风速区，由于强烈的波浪破碎而产生的夹带气泡显著地促进了传质，但分散液滴的效果可以忽略不计。降雨对气水界面传质有促进作用，降雨动量通量可以很好地描述这种促进作用。结果的细节应参考我们发表的文章。少