共查询到18条相似文献,搜索用时 187 毫秒
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该文以一组色散关系得到改进的完全非线性Boussinesq方程建立了一个波浪模型,通过与均匀水深条件下聚焦波浪的实验结果进行对比说明该模型可以很好的模拟聚焦波浪,然后应用该模型聚焦波浪在一前后坡度对称的潜堤上的非线性传播变形。结果表明:随着水深的减小波峰越来越尖,波谷越来越平坦,所对应的能谱在高次谐频部分也有较大的增长,但在堤顶部分和反变浅区域,波浪的群性随着水深的增大而越来越不明显,对应的频谱表明在这段区域内有反向能量传递存在。另外,在反变浅区域主波频率附近的自由波能量有所增加,这说明频率的峰度也会减小。 相似文献
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利用完全非线性Boussinesq方程数值模型,通过与不规则波浪理论谱、物理模型实验进行了对比验证,证明了该模型模拟不规则波浪的有效性。应用该模型研究了不规则波浪在缓坡潜堤上传播时,波浪非线性参数的变化。波浪在经过缓坡潜堤过程中,波浪的不对称度有一个由负变正的过程,并且最小值出现在堤顶前部区域,最大值出现在堤顶后部区域。波浪的偏度在变浅区逐渐增大,在堤顶中部区域达到最大值,之后偏度在反变浅区逐渐减小到零附近。极值出现的位置可能是潜堤受波浪冲刷破坏比较严重的位置。基于几个典型位置波面过程线的波形变化及其波浪谱变化分析了这些参数变化的原因。分析了变浅区、反变浅区、堤顶区三个区域不对称度和偏度随Ursell数的变化关系,并给出了变浅区和反变浅区波浪的不对称度和偏度与Ursell数之间的经验公式,并与相关研究进行了对比。 相似文献
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研究了一类含弱非线性的改进型Boussinesq水波方程,在非交错网格下,利用有限差分法建立了混合四阶Adams-Bashforth-Moulton的预报校正格式的波浪数值模型。在数值模型中,关于空间一阶导数差分格式采用四阶精度、二阶导数差分格式采用二阶精度。针对波浪的一维、二维传播变形问题进行了数值计算,并通过与相关实验结果对比分析考察了该数值模型的适用性。 相似文献
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数值模拟是求解防波堤爬高问题的重要方法。以Navier-Stokes方程为控制方程,该文建立了基于紧致插值曲线法(CIP法)的二维不可压缩流体的有限差分数值模型。通过分步算法对时间积分求解控制域,采用双曲正切函数自由面捕捉法(THINC法)对自由液面进行捕捉,采用浸入边界法IBM对固体边界进行处理,将波浪爬高问题视为固-液-气多相流问题。通过建立二维数值水槽,对波浪爬高越浪问题进行数值验证;进而在相同波浪条件下,对不同断面尺寸的复式防波堤进行波浪爬高的数值模拟。结果表明:该模型可以较好地模拟波浪过程中的变形、翻卷、破碎等强非线性现象,得出最大爬高与复式防波堤尺寸之间的关系,从而给出了最小爬高时对应的防波堤断面尺度。 相似文献
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L. H. Wiryanto 《Journal of Engineering Mathematics》2011,70(1-3):129-136
A linear model of waves propagating over a submerged porous breakwater is derived from two coupled boundary-value problems, each of which represents the governing equation in a different medium. The model is similar to the shallow-water equations (SWE), with a damping term proportional to the character of the porous breakwater. Therefore, waves traveling above the breakwater will be absorbed, and the amplitude decreases. The wave propagation passing over the submerged breakwater for monochromatic and solitary waves is analyzed. For monochromatic waves, the numerical solution agrees with the analytical. The amplitude decreases exponentially with respect to the space variable in the region above the breakwater. The reflected wave is also analyzed when the model is combined with a model using the shallow-water equations. 相似文献
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The dispersion equation is derived relating to the frequency and the phase velocity of propagation of Love waves in a nondissipative liquid filled porous solid underlain by an isotropic and homogeneous half space. The rectangular irregularity in the interface between the upper porous layer and the lower semi-infinite medium with a source in it is studied herein. The modified dispersion equation of Mal and the standard dispersion equation of Love waves are deduced as particular cases. In the present study, the frequency equation is obtained by applying the method of perturbation and the phase velocity curves have been drawn for different irregularities by using the numerical parameteric values as suggested by Biot. 相似文献
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This paper considers the effect of a hard-wall beach on the downstream side
of submerged parallel bars in a breakwater. In previous research, it was assumed that
the beach can absorb all of the transmitted wave energy, when an optimal dimension
for a submerged parallel bar is obtained and the wave amplitude is reduced as more
bars are installed. However, for a hard-wall beach there are waves reflected from the
beach that change the long-term wave interaction. We adopt the linear shallow water
equations in Riemann invariant form and use the method of characteristics, in a procedure
applicable to various formations of submerged rectangular bars. The distance from
the parallel bar (or bars) to the beach determines the phase differences between right
running waves in the beach basin and whether they superpose destructively or constructively
before hitting the beach, to define the safest and the most dangerous cases. Our
numerical calculations for one bar, two bars and for periodic rectangular bars confirm
the analytical formulae obtained. 相似文献
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《Engineering Analysis with Boundary Elements》1999,23(7):619-624
The problem of groundwater flow over sloping beds is investigated on the assumption that the streamlines are parallel to the sloping bed instead of being horizontal. The sloping bed is bounded below by an impermeable sublayer, and with the upper surface free. In this case, the resulting equation is the non-linear Boussinesq equation incorporating the slope factor. We solve this equation by a modified boundary integral procedure known as the Green element method (GEM). This numerical technique resolves the non-linearity of the governing equation efficiently and straightforwardly. Comparison of the results obtained herewith with those available in literature shows good agreement, and confirms that for a majority of practical cases, GEM simulation can be considered to be satisfactory. 相似文献
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In this paper, a nonlinear wave equation with variable coefficients is studied, interestingly, this equation can be used to describe the travelling waves propagating along the circular rod composed of a general compressible hyperelastic material with variable cross-sections and variable material densities. With the aid of Lou’s direct method1, the nonlinear wave equation with variable coefficients is reduced and two sets of symmetry transformations and exact solutions of the nonlinear wave equation are obtained. The corresponding numerical examples of exact solutions are presented by using different coefficients. Particularly, while the variable coefficients are taken as some special constants, the nonlinear wave equation with variable coefficients reduces to the one with constant coefficients, which can be used to describe the propagation of the travelling waves in general cylindrical rods composed of generally hyperelastic materials. Using the same method to solve the nonlinear wave equation, the validity and rationality of this method are verified. 相似文献
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Guided wave propagation in an elastic hollow cylinder coated with a viscoelastic material 总被引:6,自引:0,他引:6
Barshinger JN Rose JL 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2004,51(11):1547-1556
The propagation of ultrasonic guided waves in an elastic hollow cylinder with a viscoelastic coating is studied. The principle motivation is to provide tools for performing a guided wave, nondestructive inspection of piping and tubing with viscoelastic coatings. The theoretical boundary value problem is solved that describes the guided wave propagation in these structures for the purpose of finding the guided wave modes that propagate with little or no attenuation. The model uses the global matrix technique to generate the dispersion equation for the longitudinal modes of a system of an arbitrary number of perfectly bonded hollow cylinders with traction-free outer surfaces. A numerical solution of the dispersion equation produces the phase velocity and attenuation dispersion curves that describe the nature of the guided wave propagation. The attenuation dispersion curves show some guided wave modes that propagate with little or no attenuation in the coated structures of interest. The wave structure is examined for two of the modes to verify that the boundary conditions are satisfied and to explain their attenuation behavior. Experimental results are produced using an array of transducers positioned circumferentially around the pipe to evaluate the accuracy of the numerical solution. 相似文献
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Nonlinear wave propagation and run-up generated by subaerial landslides modeled using meshless method 总被引:1,自引:0,他引:1
The focus of present study is on water waves generated by landslides. Because such problems involve moving boundaries and large deformation of the computational domain, a 2-D numerical model is established with a meshless method and a fully nonlinear Lagrangian time marching scheme. The method chosen in this study is a RBF collocation method developed in the way that the collocations of both the governing equation and boundary conditions are applied at each of the boundary points. This guarantees the accuracies of the partial derivatives of the velocity potential near the free surface, which results in the precise prediction of the free surface. A very effective treatment is proposed for the landslide boundary in this study. Present model is verified by comparing the numerical results of waves generated by a submerged landslide with other numerical solutions, including those obtained using the BIEM and Boussinesq-type models. Fairly good agreements are observed. Present model is then applied to simulate subaerial landslide-induced waves. Various slopes are considered. The landslide-induced wave propagation and shoreline motions are examined. The effects of sliding horizontal distance along a given slope on the induced wave are also discussed. 相似文献