沿岸流不稳定性的实验研究及理论分析
Laboratory study and analysis of the instability of alongshore currents
-
摘要: 在坡度为1:40的平面斜坡上进行了单向不规则波的沿岸流不稳定运动实验,观测到了沿岸流的周期性波动(波动周期约为100 s)。利用最大熵方法和三角函数回归法求得这种波动的主频率以及幅值,分析了波动幅值在垂直岸线方向的变化,结果表明该变化与沿岸流变化类似,即在沿岸流最大值附近这种波动强度最大。为了分析波动的机理,利用线性沿岸流不稳定模型对模型实验结果进行了分析,求得了不稳定运动增长模式和波动周期,并与对应实测结果进行了比较,结果表明,计算结果与实测值符合,从而说明实验中观测到的这种周期性波动为沿岸流不稳定引起的剪切波。Abstract: Laboratory experiments on the instability of alongshore currents were performed on a plane beach with slope 1:40.Low-frequency fluctuations of along shore currents with the period of approximately 100 s were observed.The dominant frequency and amplitude of the oscillations of along shore currents were determined using maximumentropy method and the regression method of trigonometric function,and the results showed that the variations of the amplitude of the alongshore current oscillations were similar to the variations of the mean along shore currents in the cross-shore direction.The linear shearinstability theory was used to analyze the mechanism of the oscillation,and the calculated results agreed with measurements.This confirms that the observed fluctuations of along shore currents are due to the shearinstability of alongshore currents.
-
Key words:
- alongshore currents /
- shearinstability /
- water waves /
- coast
-
OLTMAN-SHAY J,HOWD P A,BIRKEMEIER W A.Shear instabilities of the mean longshore current:2.Field observations[J].Journal of Geophysical Research,1989,94:18031-18042. BOWEN A J,HOLMAN R A.Shear instabilities of the mean longshore current:1,Theory[J].Journal of Geophysical Research,1989,94:18023-18030. DODD N,THORNTON E B.Growth and energetics of shear waves in the nearshore[J].Journal of Geophysical Research,1990,95(C9):16075-16083. PUTREVU U,SVENDSEN I A.Shear instability of longshore currents:a numerical study[J].Journal of Geophysical Research,1992,97:7283-7303. 金红,邹志利,邱大洪,等.海岸水动力因素对污染物输移的影响[J].海洋学报,2006,28(6):144-150. 邹志利,任春平,金红,等.沿岸流不稳定性运动实验研究[G]//第十二届中国海岸工程会议论文集.北京:海洋出版社,2005:334-338. 胡广书.数字信号处理理论、算法与实现[M].北京:清华大学出版社,2003. 徐伯勋,白旭滨.最大熵谱估计在油气检测中的应用[J].石油物探,1990,29(2):1-12. 徐伯勋,白旭滨.最大熵谱估计中振幅谱和相位谱的求法[J].石油物探,1987,26(2):66-74. 张白林.杨梦岩.最大熵谱的振幅谱和相位谱计算[J].西南石油学院学报,1993,15(4):16-24. 陈哑勇.MATLAB信号处理详解[M].北京:人民邮电出版社,2001. GARBOW B S.CALGO Algorithm 535:The QZ algorithm to solve the generalized eigenvalue problem for complex matrices[J].ACM Transactions on Mathematical Software,1978,4:404-410. MOLER C,STEWART G W.An algorithm for generalized matrix eigenvalue problems[J].SIAM Journal on Numerical Analysis,1973,10:241-256. ZOU Zhi-li,WANG Shu-ping,QIU Da-hong.Longshore currents of random waves on different plane beaches[J].China Ocean Engineering,2003,17(2):265-276. -
计量
- 文章访问数: 818
- HTML全文浏览量: 20
- PDF下载量: 889
- 被引次数: 0
下载:
