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海面飞沫水滴改变着海气动量通量的分布, 从而在相当程度上影响着海面拖曳系数. 为了能够精确估计海面飞沫水滴对海面拖曳系数的影响, 推导出新的依赖于风速和海浪状态的海洋飞沫生成函数, 将该飞沫生成函数用在改进的飞沫动量通量计算公式中进行飞沫动量通量的计算, 发现本文提出的飞沫动量通量计算公式对海浪状态具有较强的敏感性, 能够清晰地表达海浪状态对飞沫动量通量的影响. 海面总动量通量包含飞沫动量通量和海气界面动量通量, 基于此理论, 得到高风速下受飞沫水滴影响的海面拖曳系数关系式, 从关系式的理论值可知, 在高风速下, 海面拖曳系数开始衰减, 说明高风速下海面飞沫水滴能够抑制拖曳系数值的增加. 将理论结果与实验室和外海测量值进行对比, 发现海面拖曳系数的理论值变化范围覆盖了测量值, 同时将该海面拖曳系数代入海浪模式进行台风浪模拟, 发现海浪模式能够较好地模拟出有效波高, 说明本文提出的新的海面拖曳系数公式能够合理地用在高风速条件下.Sea spray droplets change the distribution of air-sea momentum fluxes in the sea surface, and then influence sea surface drag coefficient considerably. In order to estimate the influence of sea spray droplets on drag coefficient exactly, a new sea spray generation function (SSGF) which depends on wind and wave, is deduced. Then the SSGF is integrated into the spray momentum flux formula to calculate the spray momentum flux. The result shows that revised spray momentum flux formula are sensitive to the wave state remarkably. It indicates that the new sea spray flux formulae can be used in any wave state. The total momentum flux of sea surface contains sea spray momentum flux and air-sea interface momentum flux. Based on this theory, the formula of drag coefficient which is influenced by sea spray droplets at high wind speed is acquired. The theoretical result of the drag coefficient formula shows that the drag coefficient reduces at the high wind speed, which indicates that the sea spray droplets can restrict the increase of drag coefficient at high wind speed. Comparison between theoretical value and measured value of sea surface drag coefficient in field and laboratory shows that the theoretical value of drag coefficient cover the measured value almost. Meanwhile, with the new sea surface drag coefficient, ocean wave model can model the significant wave height very well in typhoon condition. All the results show that the new drag coefficient can be used properly at high wind speed.
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Keywords:
- sea spray/
- drag coefficient/
- wave state
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