共查询到15条相似文献，搜索用时 109 毫秒
1.
利用准三维的ｆＫｄＶ方程及四区间划分法,理论上求得了先锋孤立子生成诸速度—先锋孤立子的运动速度、压水区中流的速度及尾波列第一个跨零点的速度。所述理论是Ｘｕ等人的先锋孤立子生成理论的一个推广。作为应用的例子,运用作者得到的理论结果,对具有相同截面面积的等腰三角形和正方形截面的直渠中先锋孤立子生成的诸速度进行了理论预报和数值比较。比较指出,理论和数值结果吻合得很好。 相似文献
2.
利用准三维的ｆＫｄＶ方程和四区间划分法,理论给出了任意截面的直渠道中先锋孤立子生成的理论平均波阻和区间平均能量的时间变化率。基于ｆＫｄＶ方程系数的正则性,文中结果是Ｘｕ等人结果的一个推广。对具有相同截面面积的正方形和等腰三角形截面的渠道及在不同强迫源和强迫源速度条件下,对理论平均波阻和平均生成能的时间变化率进行了数值比较和理论预报。比较指出,理论和数值结果吻合得很好。 相似文献
3.
用ｆＫｄＶ模式方程对单层二维表面波进行直接的数值研究。计算得出，在共振区域先锋孤立子的生成与Ｔ、Ｙ．Ｗｕ（吴耀祖）及Ｓ．Ｊ．Ｌｅｅ等人的结果相同。在共振点与超临界转向点之间，对每一个Ｆｒ数存在初始不稳定的单峰孤立子，其振幅随时间增加。当Ｆｒ数接近共振区时，初始孤立子分裂成先峰孤立子，即先峰孤立子生成是占优的。当Ｆｒ接近超临界转向点时，这类初始不稳定孤立子最终破碎。当Ｆｒ超过超临界转向点时，存在一类稳定的超临界孤立子，其振幅不随时间变化，但是它得自时间相关方程。这类孤立子位于驱动力上方，它的振幅随Ｆｒ的增加而减少．由于它不同于自由ＫｄＶ孤立子，因此本文称之为超临界驻定孤立子。 相似文献
4.
根据作者导得的AfKdV方程，理论上确定了先锋孤立子生成问题的理论平均波阻，能量劈分及能量劈分比。本文的能量劈分是确定先锋孤立子生成参数的理论基础。同时，本理论确定了现有理论中的自由未知参数问题，从而使先锋孤立子生成参数得到理论预报。 相似文献
5.
基于fKdV方程系数的正则特性，以二维两层流的先锋孤立子生成问题为算例，用数值方法对本文部分（Ⅰ）中的理论平均波阻，能量劈分及能量劈分比进行检验。从理论与数值结果的比较知，理论与数值结果符合得很好。这表明本文部分（Ⅰ）中的理论平均波阻，能量劈分及能量劈分比可用于先锋孤立子生成参数的预报，也表明本文部分（Ⅰ）中的理论可推广应用于二维非线性强迫系统。 相似文献
6.
基于MCC理论的内孤立波数值模拟 总被引：3，自引：0，他引：3
基于MCC(Miyata-Choi-Camassa)理论,将内孤立波诱导上下层深度平均水平速度为入口条件,结合理想流体完全非线性欧拉方程,建立了两层流体中内孤立波生成与传播的CFD(Computational Fluid Dynamics)数值水槽方法。在系列数值模拟基础上,获得了内孤立波设计振幅与数值模拟振幅之间的相关关系,实现了在振幅可控条件下的内孤立波数值模拟。结果表明,在极限振幅范围内,数值模拟所得内孤立波波形均与MCC理论解吻合良好,而KdV(Korteweg-de Vries)和mKdV(modi-fied KdV)理论解只适用于小振幅的情况。同时,利用CFD数值模拟结果,对内孤立波诱导流速场特性进行了分析,结果表明内孤立波诱导水平速度在上层及波面下方流体层中垂向衰减很小,但在内界面与波面之间流体层中垂向衰减明显。 相似文献
7.
本文利用1949～1986年的台风资料,统计了西北太平洋上台风逐日生成的气候概率。指出这些概率在一年中的分布是不均匀的。根据不同阶段的特征,可以划分为9个自然季节。对逐日概率的年变程进行的波谱分析表明,在一年中台风生成的逐日气候概率,主要由两部分波组成,反映季节变化的波和中短期天气过程波。季节变化波最突出,分布比较规则,由1～3个波合成已模拟得相当好。4～20波,经检验其振幅很小,被舍弃。波数小于21的波,有些振幅虽大,但周期较短,在20天以内,属天气过程波。 相似文献
8.
基于有限深两层流体KdV(Korteweg-de Vries)、eKdV(extended KdV)和MCC(Miyata-Choi-Camassa)理论,以内孤立波诱导上下层深度平均水平速度为入口边界条件,采用理想流体完全非线性欧拉方程,建立了两层流体中内孤立波生成的CFD(Computational Fluid Dynamics)数值模拟方法。以系列数值模拟结果为依据,结合内孤立波非线性和色散参数的组合条件,给出了选择合适内孤立波理论解作为CFD数值模拟入口边界条件的方法,从而实现了振幅与波形可控的内孤立波完全非线性数值模拟。 相似文献
9.
将置于大尺度密度分层水槽上下层流体中的两块垂直板反方向平推,以基于MCC理论解的内孤立波诱导上下层流体中的层平均水平速度作为其运动速度,发展了一种振幅可控的双推板内孤立波实验室造波方法,并对内孤立波作用下浮式生产储油系统(FPSO)的载荷特性开展了系列实验。结果表明,无因次内孤立波水平力和力矩幅值均与先导内孤立子无因次振幅之间呈线性关系,其斜率与上下层流体深度比有关;在各种上下层流体深度比下,无因次内孤立波垂向力幅值与先导内孤立子振幅之间近似呈幂函数关系。 相似文献
10.
基于布放在南海东北部陆坡海域的5套潜标观测到的内孤立波波列数据和孤立波扰动KdV(PKdV)理论,研究内孤立波在趋浅陆架上的传播特征。得出如下结果:1)观测到的内孤立波属于C型内孤立波,即平均重现周期为(23.41±0.31)h。2)内孤立波在西传爬坡过程中,其振幅表现为先增大后减小再增大,与该海域温跃层深度的变化趋势一致;由观测数据和理论计算得到的孤立波振幅增长率(SAGR)数值接近,表明该海域的内孤立波的振幅变化可以采用由孤立波PKdV方程导出的趋浅温跃层理论来描述。3)随着水深变浅,内孤立波传播方向向北偏移,传播速度减小,即在A,B和D站位,传播方向分别为279°,296°和301°,偏转角度达22°;传播速度分别为2.36,2.23和1.47 m/s,减小38%。 相似文献
11.
An infinity of conservation laws of fKdV equation is derived in terms of the Miura and Gardner''s transform.The pseudo-mass and energy theorems are studied by the first two conservation laws.As a typical example,the theoretical mean wave resistance and the regional distribution of energy of the precursor soliton generation are determined by means of the first and the second conservation laws. 相似文献
12.
Several ray-type 1D and 2D KdV equations for two-layer stratified ocean with topographic effect are derived in detail in the present study.A simplified version of these equations,ray type 1D KdV equation,is used to calculate numerically the disintegration of initial interface soliton from the deep sea to the continental shelf.At the same time,a laboratory experiment is carried out in a 2D stratified flow and internal wave tank to examine the numerical results.A comparison of the numerical results with the experimental results shows that they are in good agreement.The numerical results also show that the ray-type KdV equation has high accuracy in describing the evolution of initial interface waves in shelf/slope regions.Form these results,it can be concluded that the fission process is a dominant generating mechanism of interface soliton packets on the continental shelf. 相似文献
13.
Ｏｎｈｙｄｒａｕｌｉｃｆａｌｌｓｏｆｓｉｎｇｌｅ－ｌａｙｅｒｆｌｏｗ￥ＸｕＺｈａｏｔｉｎｇ；ＴｉａｎＪｉｗｅｉ；ＬｏｕＳｈｕｎｌｉａｎｄＳａｍｕｅｌＳｈａｎｐｎＳｈｅｎ（ＲｅｃｅｉｖｅｄＭａｒｃｈ２１，１９９５；ａｃｃｅｐｔｅｄＪｕｌｙ１０，１９９５... 相似文献
14.
A method for generating waves in Boussinesq-type wave models is described. The method employs a source term added to the governing equations, either in the form of a mass source in the continuity equation or an applied pressure forcing in the momentum equations. Assuming linearity, we derive a transfer function which relates source amplitude to surface wave characteristics. We then test the model for generation of desired incident waves, including regular and random waves, for both one and two dimensions. We also compare some model results with analytical solution and available experiment data. 相似文献
15.
《Oceanic Engineering, IEEE Journal of》2004,29(4):1182-1199
In a recent study, satellite images have shown that internal solitons are active in the northern South China Sea (SCS). During the Asian Seas International Acoustic Experiment (ASIAEX) pilot studies, current profiler and thermistor chain moorings were deployed in the spring of 1999 and 2000 to investigate internal solitons northeast of Tung-Sha Island on the continental slope of the northern SCS. Most of the observed internal solitons were first baroclinic mode depression waves. The largest horizontal current velocity, vertical displacement, and temperature variation induced by the internal solitons were around 240 cm/s, 106 m, and 11/spl deg/C, respectively, while the estimated nonlinear phase speed was primarily westward at 152 /spl plusmn/ 4 cm/s. The observed internal solitons could be categorized as four types. The first type is the incoming wave from deep water and can be described reasonably well with the KdV equation. The second and third types are in the transition zone before and close to the turning point (where the upper and lower layer depths are equal), respectively. These two types of solitons were generally near the wave-breaking stage. The fourth type of soliton is a second baroclinic mode and probably was locally generated. The time evolutions are asymmetric, especially at the middle depths. A temperature kink following the main pulse of the soliton is often seen. Higher order nonlinear and shallow topographic effects could be the primary cause for these features. The appearance/disappearance of internal solitons coincides mostly with spring/neap tide. The internal soliton is irregularly seen during the neap tide period and its amplitude is generally small. The time interval between two leading solitons is generally around 12 h. The first baroclinic mode of the semidiurnal tide has a larger amplitude than the diurnal tide and could redistribute its energy into the soliton. 相似文献