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一种白浪覆盖率与风要素关系模式 总被引:2,自引:0,他引:2
采用Glazm an 提出的“微尺度平均”的方法,在合理选择平均尺度的基础上计算了JONSWAP谱的四阶矩,并将此结果与Snyder提出的白浪覆盖率模式结合,从而建立起依赖于风速和风区两者的半经验、半理论的白浪覆盖率与风要素关系模式。此模式给出的结果与Monahan 等汇集的海洋白浪覆盖率测量数据总体符合良好。 相似文献
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由运动方程和涡度方程所导得的两个首次积分估计给出了海波破碎的发生条件和破碎波的波面限制。由这两个条件所构造的新的破碎波统计模式,可导出海波的破碎面积率、破碎体积率和破碎能量损耗率的解析表达式,加之一个简单的白冠物理模型又导出了一个新的白冠覆盖率的解析表达式。 相似文献
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利用已有风浪破碎实验观测数据检验了风浪破碎判据的可靠性。实验测量了风浪波面位移的时间序列,并人工同步标记出破碎发生的时刻。研究了4种常用判据,包括波陡、瞬时波面斜率、波峰水质点水平速度与相速度之比,以及波峰水质点向下加速度与重力加速度之比。采用破碎判据对所测风浪序列中的破碎波进行识别,根据人工标记数量计算破碎率以确定破碎阈值。计算结果表明,几何判断阈值接近Stokes波极限值,而运动学和动力学判断阈值则明显偏离。进而检验了判据识别出的破碎波与人工标记破碎波的一致性。在达到破碎阈值的波中,约35%~55%与人工标记相对应,约有45%~65%的波,虽然满足了阈值条件,却并未发生破碎,说明风浪的破碎可能并非完全取决于其中任一判据所关注的波浪特征量。 相似文献
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波浪破碎是一个强非线性过程,破碎时产生的大量气泡在海面上表现为白冠,白冠覆盖率是刻画波浪破碎一个重要参数。研究表明,白冠覆盖率与海上风速、海浪状态和大气稳定度等多种海洋环境因素有关。综合前人的观测数据,本文给出了更为可靠的依赖风速的白冠覆盖率公式,发现海水温度越高,白冠覆盖率越大。提出了以波浪破碎耗散函数为参数的白冠覆盖率公式,同时发现波龄小于某个临界值时,白冠覆盖率随波龄增大,波龄大于临界值时,白冠覆盖率保持不变,该临界值随风速增大而减小。 相似文献
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More and more researches show that neither the critical downward acceleration nor the critical slope of water waves is a universal constant. On the contrary, they vary with particular wave conditions. This fact moders the models either for the probability of wave breaking B or for the whitecap coverage W based on these criteria difficult to apply. In this paper and the one which follows we seek to develop models for the prediction of both B and W based on the kinematical criterion. First, several joint probabihstic distribution functions (PDFs) of wave characteristics are derived, based on which the breaking properties B and W are estimated. The estimation is made on the assumption that a wave breaks ff the horizontal velocity of water particles at its crest exceeds the local wave celerity, and whitecapping occurs in regions of fluid where water particles travel faster than the waves. The consequent B and W depend on wave spectral moments of orders 0 to 4.Then the JONSWAP spectrum is used to represent the fetch-limited sea waves in deep water, so as to relate the probahility of wave breaking and the whitecap coverage with wind parameters. To this end, the time-averaging technique proposed by Glazman (1986) is applied to the estimation of the spectral moments involved, and furthermore, the theoretical models are compared with available observations collected from published literature. From the comparison, the averaging time scale is determined. The final models show that the probability of wave breaking as well as the whitecap coverage depends on the dimensionless fetch. The agreement between these models and the database is reasonable. 相似文献
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南沙海区风浪分析与计算 总被引:3,自引:0,他引:3
根据南沙海区风浪实测资料,阐述了南沙海区波高的分布规律。应用相关分析法,通过多元回归计算,得出波要素与风速、风时之间的关系。对波高、波周期的相互关系作了统计分析并利用永署礁海洋观测站1990年1~7月的实测资料对计算结果作了验证。结果表明,南沙海区波高、波周期的计算值与实测值基本吻合。 相似文献
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基于实验室水槽实验,研究了内孤立波在海底山脊地形存在下的破碎过程。实验设置了两层流体的分层环境,定量地控制了上下层水体厚度及密度,使用不同高度的高斯地形模拟实际的海山作用,讨论了不同高度地形作用下内孤立波破碎过程的异同。实验结果表明,内孤立波的破碎过程中由于逆压梯度的存在,在地形处发生边界层分离,产生了底边界层反向射流和涡脱落现象,计算了内孤立波破碎过程中产生的底部切应力的分布。本文通过实验模拟了内孤立波再海山作用下的破碎过程,进一步探究了海山对内孤立波破碎的影响和底部切应力的作用,对于研究自然界中海洋内孤立波在海山区域的破碎现象有参考价值。 相似文献
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Xu Delun Yu Dingyong Lu Hongmin Professor Physical Oceanography Laboratory Ocean University of Qindao Qingdao Associate Professor Engineering School Ocean University of Qindao Qingdao Senior Engineer Physical Oceanography Laboratory Ocean University of Qingdao Qingdao 《中国海洋工程》1998,(1)
Using the limit surface slope as a criterion of wave breaking,a simple model for estimatingthe spatial fraction of breaking surface of sea at an instant,which is regarded as the whitecap coverge inthis paper,is analytically derived from the probability density of surface slope based on Gaussianstatistics.The resulting fraction is found depending on the fourth moment of wave spectum,m_4,as well asthe critical threshold of surface slope.By expressing the fourth moment in terms of the Neumannspectrum,a formula linking the fraction and wind speed for fully developed sea states is obtianed.Anotherformula relating the fraction to both wind speed and fetch(or duration)is achieved by expressing m_4 interms of the Krylov spectrum and applying the empirical relationships used in the SMB ocean wave pre-dicting technique.A comparison between these results and the field data of whitecap coverage collected byMonahan and O'Muircheartuigh shows an encouraging agreement. 相似文献
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1 .Introduction Wave breaking and associated whitecapping have long beeninteresting due totheir close relationto many fields of ocean study,including air-sea interaction,remote sensing,ocean engineering,aswell as wave dynamics .The breaking probabilityBan… 相似文献