摘要
海浪的群性是海浪场的一种重要特性,它对海堤的损毁,港湾共震,浮体结构物的动力反应等有明显影响,因此,在海洋工程设计中需要进行波群对建筑物作用的试验,这就要求模拟波群。目前随机波群模拟的研究大多限于单向波,而实际的海浪是多方向的,所以对多向随机波群模拟的研究具有很重要的理论意义和工程应用价值。
论文首先介绍了研究波群的主要方法和目前常用的描述波浪群性的参数,由实测波浪资料,对描述群性的高度与长度特征参数之间的相关性进行了分析。同时应用基于小波变换所得小波波能过程定义了两个新的群性参数,并由数值模拟波浪和实测波浪资料对其与常用的波群参数进行对比分析,结果表明基于小波波能过程定义的群性参数是有效的,从而展示了小波变换用于在时频域上分析波群的能力。并详细探讨了波浪记录长度对群性参数稳定性的影响,分析结果表明波浪观测长度对于波群参数的影响较大,在考虑波浪群性的波浪模拟及分析时,建议模拟时间长度应在400~500个波以上。
根据渤海和珠江口两地的波浪观测数据,采用合理的无因次化方式,拟合得到一个适于风浪的波包谱经验公式。该公式同时考虑了群高与群长两方面的因素,并依据对实测波浪资料波群参数的分析结果给出了较合理的参数取值范围,只要给出波要素和波群的特征参数即可确定波包谱形,便于实际应用。
然后,以建议的经验波包谱作为靶谱,建立了单向不规则波群的数值模拟方法,模拟实例表明,只要给定波要素及描述波浪群性的高度特征参数和长度特征参数,即可通过波包谱方便地模拟出同时满足给定高度和长度两方面群性特征要求的不规则波群。在此基础上,建立了在水槽中指定位置处产生不规则波群的造波机控制信号的计算方法,在实验室成功地模拟了同时满足频谱及群性要求的波浪。并对实验模拟的不同群性的波浪在水槽传播过程中群性的变化进行了分析,结果表明波浪在传播过程中,由于谐波的调制作用,波浪的群性会趋于某一有限的范围,在进行考虑波浪群性的物理模型实验时,需在水槽中指定位置处产生满足模拟要求的波浪。
进一步,在单向不规则波群模拟研究的基础上,引进方向分布函数,建立了可有效地数值模拟多向不规则波群的方法。然后建立了能够应用于模拟多向不规则波群传播的数值计算模型的入射波浪边界条件,对多向不规则波群的传播进行了数值模拟和分析,可以在数值水池指定位置处产生满足给定群性要求的多向不规则波浪。在此基础上,建立了在物理水池中指定位置处产生多向不规则波群的造波机控制信号的计算方法,并开展了多向不规则波群的物理模拟实验,在实验水池中指定位置处成功地模拟了满足给定群性和方向分布要求的多向不规则波浪,同时分析了不同群性的多向不规则波浪在水池传播过程中群性的变化。
最后,由数值模拟的多向波群和实测波浪资料分析了波浪的群性对其特征波高和波高分布的影响,结果表明波浪特征波高随群高增大而增大,且最大波高受群高影响最大,但与群长无明显关系,并分析得到了威布尔分布的参数α、β与群高GFH的关系式。
Wave groupiness is an important characteristics of the ocean waves.It has obvious effects on the damage of the seawall,harbor resonance and the response of floating structures, etc. Hence, tests on the effects of wave groups on the structures have to be involved for the design of the ocean structures, which requires simulating wave groups. So far, the studies on the simulation of random wave groups are mostly confined to the unidirectional waves.However, the real ocean waves are multidirectional waves.So, the study on the simulation of multidirectional random wave groups has very important theoretical importance and application value for engineering.
At the beginning of this paper, the main approaches to research wave groups and the parameters commonly used to describe the wave groupiness degree are introduced. Correlation of the main characterisitic parameters to describe wave group height and group length is analyzed based on the field measured wave data. At the same time, two new factors to describe wave groupiness based on the wave energy history deduced by wavelet transform are defined.Through numerically simulated wave and the field wave data, their effectiveness is confirmed by the comparation with the commonly used wave groupiness parameters. Therefore, the ability of the wavelet transform to analyze wave groupiness in time-frequency domain is demonstrated.Further, the effects of the wave record length on the stability of the wave groupiness factors are discussed in detail.The analyzed results indicate that the wave record length has great effects on the wave groupiness parameters,and it is suggested that, for the simulation and analysis of waves considering wave groupiness,the number of waves during the simulation time length should be at least400to500.
An empirical wave envelope spectrum suitable for wind waves is obtained by fitting to the reasonablely normalized wave envelope spectra of the measured sea waves at the mouth of the Zhu Jiang River and in the Bohai Sea. In the proposed wave envelope spectrum,both the wave group height and group length are considered.In addition, more reasonable parameter selection principle is given according to the analysis results of the wave group chracterisitics of the field wave data. It can be determined provided that the wave parameters and wave groupiness factors are given. So, it is feasible for practical application.
Then, based on the improved empirical wave envelope spectrum, a method to simulate unidirectional irregular wave groups is developed.Simulation examples demonstrate that, irregular wave groups which includes not only its group height but also its length can be conveniently simulated by the empirical wave envelope spectrum,provided that the wave parameters and the parameters for the description of the wave group height and group length are given. Then, the calculation method of the wave maker signals for generating irregular wave groups at the specified position in the wave flume is proposed.Random waves containing expected wave groupiness and wave spectrum are satisfactorily simulated in laboratory wave flume. In addition, the variations of wave groupiness for the simulated waves with different wave groupiness during propagation in the wave flume are investigated.The analyzed results demonstrate that wave groupiness tends to be an limted range along with wave propogation due to the modulation of harmonic waves.It means that, for physical model tests considering wave groupiness, the waves with desired wave groupiness should be generated at the specified position in the wave flume
Further, based on the study of the simulation of unidirectional wave groups,the method to simulate multidirectional wave groups is developed by introducing directional spreading function. The calculation method for the incident boundary condition of the numerical wave basin used to generate multidirectional waves containing expected wave groupiness is proposed. Using the numerical model, the multidirectional wave propogation is numerically simulated and analyzed. Multidirectional wave groups can be generated at the specified position in the numerical wave basin. Then, the calculation method of the wave maker driving signals for generating multidirectional wave groups in physical wave basin is proposed.The physical simulation of multidirectional wave groups is performed in physical wave basin. The multidirectional waves with expected wave groupiness and directional spreading can be satisfactorily generated at the specified position in the physical wave basin. The variations of wave groupiness for the experimentally simulated waves during propogation in the physical wave basin are also analyzed.
Last, the effects of wave groupiness on the characteristic wave heights and wave height distribution are analyzed through numerically simulated multidirectional wave groups and the field wave data. The results show that the characteristic wave heights increase with the wave group height, moreover, the maximum wave height is effected mostly by the wave group height. But, they have little corelation with the wave group length.The relation between the parameters α、β of the Welbull distribution and wave group height is obtained.
引文
[1]Nolte K G, Hsu F H. Statistics of Ocean Wave Groups [C].Fourth Annual Offshore Technology, Houston, Texas,1972,2:637-644.
[2]Goda Y. Numerical experiments on wave statistics with spectral simulation[R]. Report of the Port and Harbour Research Institute,1970,9(3):3-57.
[3]Rye H. Ocean wave groups [R]. Report UR-82-18. Trondheim:Dept. of Marine Techno 1., Univ. of Trondheim,1982.
[4]Mollo-Christensen E, Ramamonjiarisoa A. Modelling the presence of wave groups in a random wave field [J]. Journal of Geophysical Research,1978,83(C8):4117-4112.
[5]Kuznetsov AI et al. Load analysis from wave groups [C]. Proceedings of the 16th Coastal Engineering Conference,Hamburg,1978, (3):2328-2329.
[6]Shand T D, Peirson W L, Cox R J. Engineering design in the presence of wave groups [J]. Coastal engineering,2010.
[7]Funke E R, Mansard E P D. On the synthesis of realistic sea states in laboratory flume [C].Proc I7th International Conf. on Coastal Engineering, Sydney,1980,3:2974-2991.
[8]Kimura A. Statistical properties of random wave groups [C]. Proc I7th International Conf. on Coastal Engineering, Sydney:ICCE,1980,3:2955-2973.
[9]Battjes J A, Van Vledder. Verification of Kimura's theory for wave group statistics[C]. Proc.19th Conf. on Coastal Eng. Houston,1984,642-648.
[10]Elgar S, Guza R T, Seymour R J. Group of waves in shallow water [J].Journal of Geophysical Research,1984,89 (C3):3623-3634.
[11]Masson D, Chandler P. Wave groups:a closer look at spectral methods [J]. Coastal Engineering,1993,20:249-275.
[12]Yuen H C, Lake B M. Instabilities of waves on deepwater [J]. Journal of Fluid Mechanics,1980,12,303-334.
[13]Mase H, Kita N, Iwagaki Y. Random wave simulation considering wave groups [J]. Coastal Engineering in Japan,1983,26:61-75.
[14]Ewing J A. Mean length of runs of high waves [J]. Journal of Geophysical Research, 1973,78(12):1933-1936.
[15]俞聿修.随机波浪及其工程应用[M].大连:大连理工大学出版社,1992.
[16]Sawnhey M D. A study of ocean wave amplitudes in terms of the theory of runs and a Markhov chain process.1962.
[17]Goda Y. Analysis of wave grouping and spectra of long-travelled swell[R]. Report of the Port and Harbour Research Institute,1983,9:3-75.
[18]Thomas K V, Baba M, Harish C M. Wave groupiness in long-traveled swell [J]. Journal of Waterway, Port, Coastal and Ocean Engineering,1986,112(4):498-511.
[19]Liu Z, Elgar S, Guza R T. Groups of ocean waves:Linear theory, approximations to linear theory, and observations [J]. Journal of Waterway, Port, Coastal and Ocean Engineering, ASCE,119(2):144-159
[20]Longuet-Higgins M S. The statistical analysis of a random moving surface [J]. Mathematical and Physical Sciences,1957,A249:321-387.
[21]Rice S 0. The mathematical analysis of random noise [J].Bell Systems Tech., 1945,24:46-156.
[22]Ochi M K, Sahinoglou I I. Stochastic characteristics of wave groups in random seas [J]. Applied Ocean Research, Part 1,1989,11(1);Part 2,1989,11(2),89-99.
[23]Longuet-Higgins M S. Statistical properties of wave groups in a random sea state[J]. Mathematical and Physical Sciences,1984,312(A):219-250.
[24]Chandler P, Masson D. Wave groups in coastal waters [C].Proc.3rd Int.Symp. On Wave Hindcasting and Forecasting, Montreal,1992,79-88.
[25]Tayfun M A. Narrow-band nonlinear sea waves [J]. Geophys Res,1980,85(c3):1548-1552.
[26]Tayfun M A. On narrow-band representation of ocean waves[J]. Geophys Res,1986, 91(C6):7743-7752.
[27]Tayfun M A, Lo J M. Wave envelope and related spectra [J]. Journal of Waterway, Port, Coastal and Ocean Engineering, ASCE,1989,115:515-533.
[28]Xu D L, Hou W, ZHAO M, WU J. The statistical simulation of wave groups [J]. Applied Ocean Research,1993,15:217-226.
[29]俞聿修,桂满海.海浪的群性及其主要特征参数[J].海洋工程,1998,16(3):9-21.
[30]俞聿修,桂满海.波群的数值模拟和物理模[J].大连理工大学学报,1998,38(1).
[31]葛明达.连云港的波群统计分析[J].黄渤海海洋,1986,4(2):4-14.
[32]常德馥.胶州湾的波群统计分析[J].海岸工程,1987,6(1):32-43.
[33]俞聿修,柳淑学.海浪的波群特性[J].港口工程,1988,5:1-7.
[34]黎满球.香港附近海区台风波浪的波群统计分析[J].热带海洋,1994,13(4):9-16.
[35]范顺庭,王以谋,王涛.渤海海浪波高群性特征的分析[J].海洋科学集刊,1998,40:13-22.
[36]Vanmarcke E H. On the distribution of the first-passage time for normal stationary random processes [C]. American Society of Mechanical Engineers, Applied Mechanics Western Conference, University of Hawaii, Honolulu,1975.
[37]Ditlevson 0, Lindgren G. Empty excursion envelopes in stationary Gaussian p rocesses [J].Journal of Sound and Vibration,1988,122(3):571-587.
[38]郑桂珍,黄旭仁,徐德伦.空波包理论在海浪群性研究中的应用[J].青岛海洋大学学报,2002,32(5):673-679.
[39]Kuznetsov S Y, Saprykina Y V. An experiment study of near-shorc evolution of wave groups [J]. Marine Physics,2002,42(3),356-363.
[40]Goda Y. On wave groups [C]. Proc. Conf. Behaviour of Offshore Structures,1976, 1:115-128.
[41]Medina J R, Hudspeth R T. Analysis of wave groups in random fields [C].Proc, Ocean structural dynamics symp,1988,88:104-118.
[42]Medina J R, Hudspeth R T. A review of the analyses of ocean wave groups [J].Coastal Engineering,1990,14:515-542.
[43]Liu P C. Wave grouping characteristics in nearshore Great Lakes [J].Ocean Engineering,2000,27:1221-1230.
[44]Veltcheva A D. Wave and group transformation by a Hilbert spectrum [J]. Coastal Engineering,2002,44(4):283-300.
[45]Huang M C. Wave parameters and functions in wavelet analysis [J]. Ocean Engineering,2004,31:111-125.
[46]Huang M C. Wave parameters and functions in wavelet analysis with filtering [J]. Ocean Engineering,2004,31:813-832.
[47]Dong G H, Ma Y X, Ma X Z. Cross-shore variations of wave groupiness by wavelet transform [J]. Ocean Engineering,2008,35:676-684.
[48]高志一,文凡.波群结构和波群中的波破碎[J].中国海洋大学学报,2010,40(9):008-014.
[49]Rye H. Wave group formation among storm waves[C]. Proc 14th Inter Conf on Coastal Eng,1974,1:164-183.
[50]Johnson R R, Mansard E P D, Ploeg J. Effects of wave grouping on breakwater stability [C].Proc 21th International Conf. on Coastal Engineering, ASCE,1978,2228-2243.
[51]Mansard E P D, Pratte B D. Moored ship response in irregular waves[C]. Proc I7th Int. Conf. on Coastal Engineering, Capetown, Sourth Africa,1982.
[52]杨正已,左其华,苏卫东.波群的实验室模拟和分析[J].海洋工程,1991,9(1):61-67.
[53]杨正已,左其华.不规则波波群对桩力的影响[J].海洋工程,1993,2.
[54]List J H. Wave groupiness variations in the near shore [J]. Coastal Engineering,1991,15:475-496.
[55]Medina J A, Hudspeth R T. A review of the analyses of ocean wave groups [J]. Coastal Engineering,1990,14:515-542.
[56]陈伯海,王炳祥.现有波群因子的统计研究[J].海洋学报,1998,20(4):133-139.
[57]赵锰等Hilbert变换在波群研究中的应用[J].海洋学报,1990,12(3):284-290.
[58]Todd L. Walton Jr, Richard Weggle J. Stability of Rubble Mound Breakwaters [J]. Journal of the Waterway Port Coastal and Ocean Division,1981,107(3):195-201.
[59]徐德伦,于定勇.随机海浪理论[M].北京:高等教育出版社,2001.
[60]Mase, H. Groupiness factor and wave height distribution [J]. Journal of Waterway, Port, Coastal and Ocean Engineering,1989,115(1):105-120.
[61]周家宝,章家昌,陈国平,王红.波群对波浪爬高影响的研究[J].水运工程,1992,6:32-37.
[62]Balaji R, Sannasiraj S A, Sundar V. Laboratory simulation and analysis of wave groups[C]. The 25th International Conference on Offshore Mechanics and Arctic Engineering,2006, Hamburg, Germany. Volume 2:Ocean Engineering and Polar and Arctic Sciences and Technology.
[63]Balaji R, Sannasiraj S A, Sundar V. Detection of wave groups from the motion behaviour of a discus buoy [J]. Journal of Hydro-environoment Research,2008,1(3):195-205.
[64]柳淑学,包艳,俞聿修.多向不规则波群的数值模拟[J].水道港口,2006,27(5):273-278.
[65]Holthuijsen L H, Herbers T H C. Statistics of breaking waves observed as whitecaps in the open sea [J]. Journal of Physical Oceanography,1986,16:290-297.
[66]Dold J W. An eff icient surface integral algorithm applied to unsteady gravity waves [J]. Journal of Computational Physics,1992,103:90-115.
[67]Nepf H M, Wu C H, Chan E S. A comparison of two and three dimensional wave breaking [J]. Journal of Physical Oceanography,1998,28:1496-1510.
[68]Banner M L, Babanin A V, Young L R. Breaking probability for dominant waves on the sea surface [J]. Journal of Physical Oceanography,2000,30:3145-3160.
[69]Svendsen L A, Veeramony J. Wave breaking in wave groups [J]. Journal of Waterway, Port, Coastal and Ocean Engineering,2001,127(4):200-212.
[70]Banner M L, Song J.2002 On determining the onset and strength of breaking for deep water waves. Part 2:Influence of wind forcing and surface shear [J]. Journal of Physical Oceanography,32:2559-2570.
[71]Banner M L, Peirson W L. Wave breaking onset and strength for two-dimensional deep-water wave groups [J]. Fluid Mechnics,2007,585:93-115.
[72]Shand T D, Peirson W L, Cox R J. On the influence of wave groups on shoaling and breaking waves [J]. Coastal Engineering,2008:94-106.
[73]Goda Y. Random Seas and Design of Maritime Structures [M]. University of Tokyo Press,1985.
[74]Munk W H. Surf beat[J]. Trans. Am. Geophys,1949,30:849-854.
[75]Tucker M J. Surf beats:Sea waves of 1 to 5minutes period [C]. Proceedings of the Royal Society, Ser.A:Mathematical physical and Engineering Sciences,1950,202:565-573.
[76]Longuet-Higgins M S, Stewart R W. Radiation stress and mass transport in gravity waves, with application to surf-beats [J].Journal of Fluid Mechanics,1962,13:481-504.
[77]Symonds G, Huntley D A, Bowen A J. Two-dimensional surf beat:long wave generation by a time-varying breakpoint [J]. Journal of Geophysical Research.1982,87:492-498.
[78]Schaffer H A, Svendsen I A. Surf beat generation on a mild-slope beach [C]. Proceedings of 21st International Conference on Coastal Engineering,Torremolinos, Spain,1988: 1058-1072.
[79]Baldock T E, Huntley D A, Bird P A D, et al. Breakpoint generated surf beat induced by bichromatic wave groups [J]. Coastal Engineering,2000,39(2-4):213-242.
[80]Baldock T E, Huntley D A. Long-wave forcing by the breaking of random gravity waves on a beach [C].Proceedings of the Royal Society A:Mathematical, Physical and Engineering Sciences,2002,458:2177-2201.
[81]Ketabdari M J, Nobari M R H, Moradi Larmaei M. Simulation of waves group propagation and breaking in coastal zone using a Navier_Stokes solver with an improved VOF free surface treatment [J]. Applied Ocean Research,2008,30,130-143.
[82]常梅.海岸低频波浪及其引起的变形[D].大连:大连理工大学,1998
[83]卢卫.海岸低频波浪数值模拟[D].大连:大连理工大学,2004
[84]刘艳莉,邹志利,尹晶.双波群产生的低频波浪的实验研究[J].中国科技论文在线,2008,3(7):477-484.
[85]Janssen T T, Kamphuis J W, Van Dongerent A R, et al. Observations of long waves on a uniform slope [J]. Coastal Engineering,2000,2:2192-2205
[86]Janssen T T, Battjes J A, Van Dongeren A R. Long waves induced by short-wave groups over a sloping bottom [J]. Journal of Geophysical Research,2003,108(C8):3252.
[87]Mase H, Iwagaki R. Run-up of Random waves on Gentle Slopes[J]. Coastal Engineering,1984,593-609.
[88]Yoshimichi Y, VT Ca, Tanimoto K, et al. Effect of wave groups and wind speedtowave overtopping [J]. Coastal Engineering,2000,2142-2155.
[89]Ketabdari M J. Mechanism of vortex generation on ripple beds and its effect on sediment transport in the sea [C]. International Conference on Coasts, Ports and Marine Structures, Ramsar,Iran,2002,296-305.
[90]Baldock T E, Manoonvoravong P, Son Pham K. Sediment transport and beach morphodynamics induced by free long waves, bound long waves and wave groups [J].Coastal Engineering,2010,57(10):898-91.
[91]Mansard E P D, Sand S E. Towards improved concepts for the description of wave grouping[C]. The 11th International Conference on Offshore Mechanics and Arctic Engineering, Calgary, Canada.1992,1-B, Offshore Technology,535-542.
[92]Bruun P. Design and construction of mounds for breakwaters and coastal protection [M]. New York:Elsevier Science Pub. Co., Inc.,1985.
[93]Burcharth H F. The effect of wave grouping on-shore structures [J].Coastal Engineering,1979,2:189-199.
[94]Jentsje W. Vander M. Stability of breakwater armour layers:Deterministic and Probabilistic Design [J]. Coastal Engineering,1987,11(3):219-239.
[95]Kevin R. Influence of wave groups on stability of berm breakwaters [J]. Journal of Waterway, Port, Coastal, and Ocean Engineering,1994,120(6):630-636.
[96]Medina JR, Fassardi C, Hudspeth R T. Effects of wave groups on the stability of rubble mound breakwaters [C]. Proceedings of 22nd International Conference on Coastal Engineering Delft,1990,1552-1563.
[97]Morlet J, Arens G, Fourgeau I, et al. Wave propagation and sampling theory [J]. Geophysics,1982,47:203-236.
[98]Torrence C, Compo G P. A practical guide to wavelet analysis [J]. Bulletin of the American Meteoro-logical Society,1998,79:61-78.
[99]Dean R G, Dalrymple R A. Water wave mechanics for engineers and scientists[M]. US:Prentice-Hall Inc,1984.
[100]Cherneva Z, Velcheva A. Wave group analyses based on phase properties[C]. Proceedings of the First International Conference on the Mediterranean Coastal Environment, Antalya,1993,1213-1221.
[101]Mase H, Kita N, Iwagaki Y. Random wave simulation considering wave groups[J].Coastal Engineering in Japan,1983,26:61-75.
[102]Goda Y A. A comparative review on the functional forms of directional wave spectrum [J]. Coastal Engineering,1999,41(1):1-20.
[103]孙忠滨,柳淑学,李金宣.基于改进Boussinesq方程的三角形网格有限元模型[J].海洋工程,2010.28:50-58.
[104]Li Y S, Liu S X, Yu Y X, et al. Numerical modeling of boussinesq equations by finite element method[J]. Coastal Engineering,1999,37(2):97-122.