共查询到19条相似文献，搜索用时 125 毫秒
1.
在快速模拟波浪运动的谱方法基础上,引入造波边界,建立了模拟波浪产生和运动的二阶计算模型。采用摄动展开方法简化了带有造波边界的水波运动问题,将速度势分解,得到了满足造波边界和自由面边界的速度势的一般解,运用快速Fourier变换和时间积分,建立了模拟波浪产生和运动的数学模型。基于该模型,采用不同的数值造波条件,模拟了波浪的产生问题;考虑了波浪的初始运动问题;通过把数值结果与物理实验的比较,验证了波浪计算模型的有效性。 相似文献
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基于势流理论和时域高阶边界元方法,建立了三维完全非线性数值波浪水槽模型.利用源造波法产生入射波浪,应用五阶斯托克斯波理论给定波浪速度;采用混合欧拉-拉格朗日方法追踪流体瞬时水面,将二阶泰勒级数展开法应用于更新下一时间步的波面和速度势;通过加速势的方法准确计算自由水面速度的法向导数和物面速度势的时间导数.对完全非线性波浪进行了模拟,得到了稳定的波形.当波浪非线性较小时,与四阶Runge- Kutta法(RK4)计算结果和五阶斯托克斯波理论解均吻合良好;随着波浪非线性的增大,计算结果误差逐渐增大.通过数值试验分析,在满足精度要求的基础上,本方法计算时间略大于四阶Runge- Kutta法的四分之一,大大减少了计算量. 相似文献
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缓坡方程是描述近岸波浪运动较好的数学模型之一。在发展的自适应有限元求解缓坡方程的基础上,采用迭代求解的方法,确定波浪相对于边界的入射方向,从而对边界条件进行改进,建立了求解缓坡方程的数值计算模型。典型算例表明,考虑波浪相对于边界的入射角度后,模型可以更好地模拟吸收波浪边界,同时对多向波对双突堤的绕射进行了模拟研究,与试验结果比较表明,所建立的数值计算模型能够适用于多向不规则波传播过程的模拟研究。 相似文献
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基于高阶边界元的三维数值波浪港池 总被引：8，自引：1，他引：8
初步建立了一个基于高阶边界元的三维数值波浪港池，港池具有造波和消波功能。采用高阶边界元16节点四边形单元和基于二阶显式泰勒展开的混合欧拉-拉格朗日时间步进求解带自由表面的完全非线性势流方程。模型中对于影响数值精度的问题作了细致的处理。数值计算结果表明本港池可以用来模拟非线性波浪的传播，具有很高的数值精度和稳定性。 相似文献
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基于推板造波理论和摇板造波理论,在Open FOAM平台上采用重叠网格技术建立黏性数值波浪水槽,并使用一种结合SIMPLE算法和PISO算法的PIMPLE算法对数值模型进行求解。利用开发的数值模型通过数值收敛性测试和网格独立性测试分别重点研究了时间步长、库朗数和网格尺寸对数值精度和计算效率的影响。并对比研究了此数值模型分别嵌入层流模型和湍流模型的计算精度和计算效率。实现的规则波和二阶有限振幅波与理论结果和试验结果吻合,验证了此黏性数值波浪水槽的造波和主动消波功能。基于二维数值波浪水槽,进一步研究了三维数值造波,数值计算结果与理论结果吻合良好。研究结果不仅验证了重叠网格在二维和三维两相流体域中求解运动物体与流场交互的可靠性和正确性,而且为使用此黏性数值波浪水槽解决更复杂的海洋工程问题提供了依据。 相似文献
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本文在时域非线性数值波浪水槽中，研究了不同风速条件下极端波浪的特性。采用推板造波的方式生成非线性波浪，基于Jeffrey遮蔽理论将风压项引入自由面动力学边界条件来模拟风压作用，通过高阶边界元法和混合欧拉-拉格朗日时间步进法来求解初边值问题。通过与已发表的聚焦波群实验结果对比验证了该数值模型的准确性，并研究了风压对极端波浪的最大波高、聚焦位置的偏移和波浪谱的演变等波浪性质的影响。本文进一步在数值波浪水槽中引入均匀水流，来模拟风生流对波浪演变的影响。结果表明，风压的存在会少量增大极端波浪的最大波高，波浪的聚焦和解焦过程伴随着明显的能量传递，并且风生流进一步导致了波浪聚焦位置的偏移。 相似文献
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港口中系泊船在波浪作用下运动问题的本质是浅水波浪与浮体的相互作用。与深水情况不同,浅水问题应当考虑水底、水域边界的影响及浅水波浪自身的特性,单一模型很难实现该模拟过程。为此,建立了Boussinesq方程计算入射波和Laplace方程计算散射波的全时域组合计算模型。有限元法求解的Boussinesq方程能使入射波充分考虑到水底、水域边界的影响和浅水波浪的特性;散射波被线性化,采用边界元法求解,并以浮体运动时的物面条件为入射波和散射波求解的匹配条件。该方法为完全的时域方法,计算网格不随时间变动,计算过程较为方便。通过与实验及其他数值方法的结果进行比较,验证了本模型对非线性波面、浮体的运动都有比较理想的计算结果,显示了本模型对非线性问题具有较好的计算能力。 相似文献
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准确确定越浪量对于斜坡堤设计有重要意义。利用格子Boltzmann方法(LBM),并采用主动吸收式速度入口造波、出流边界消波、VOF方法追踪自由表面以及静态Smagorinsky模型模拟紊流运动,建立二维数值波浪水槽,对光滑斜坡堤上规则波与不规则波越浪进行数值模拟。模拟结果与试验值及其他数值模型结果比较表明,二维LBM数值波浪水槽具有模拟斜坡堤越浪的能力,但对于破碎较为剧烈的越浪过程模拟,该模型还存在一定的不足,未来可从提高自由表面模型精度等方面进一步改善其性能。 相似文献
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非静压波浪模型是一种近年来得到迅速发展且有望在工程计算中获得广泛应用的波浪模型。为了在非静压波浪模型中实现无反射造波,在连续性方程中添加了质量源项进行域内源造波,并采用阻尼消波方法进行数值消波。数值算例结果表明,所建立的无反射造波方法可以较好地避免非静压波浪数学模型中的二次反射,实现长时间稳定波浪模拟。 相似文献
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A numerical model for coastal water wave motion that includes an effective method for treatment of non-reflecting boundaries is presented. The second-order one-way wave equation to approximate the non-reflecting boundary condition is found to be excellent and it ensures a very low level of reflection for waves approaching the boundary at a fairly wide range of the incidence angle. If the Newman approximation is adopted, the resulting boundary condition has a unique property to allow the free propagation of wave components along the boundary. The study is also based on a newly derived mild-slope wave equation system that can be easily made compatible to the one-way wave equation. The equation system is theoretically more accurate than the previous equations in terms of the mild-slope assumption. The finite difference method defined on a staggered grid is employed to solve the basic equations and to implement the non-reflecting boundary condition. For verification, the numerical model is then applied to three coastal water wave problems including the classical problem of plane wave diffraction by a vertical circular cylinder, the problem of combined wave diffraction and refraction over a submerged hump in the open sea, and the wave deformation around a detached breakwater. In all cases, the numerical results are demonstrated to agree very well with the relevant analytical solutions or with experimental data. It is thus concluded that the numerical model proposed in this study is effective and advantageous. 相似文献
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A finite element model of Boussinesq-type equations was set up, and a direct numerical method is proposed so that the full reflection boundary condition is exactly satisfied at a curved wall surface. The accuracy of the model was verified in tests. The present model was used to further examine cnoidal wave propagation and run-up around the cylinder. The results showed that the Ursell number is a nonlinear parameter that indicates the normalized profile of cnoidal waves and has a significant effect on the wave run-up. Cnoidal waves with the same Ursell number have the same normalized profile, but a difference in the relative wave height can still cause differences in the wave run-up between these waves. The maximum dimensionless run-up was predicted under various conditions. Cnoidal waves hold entirely distinct properties from Stokes waves under the influence of the water depth, and the nonlinearity of cnoidal waves enhances rather than weakens with increasing wavelength. Thus, the variations in the maximum run-up with the wavelength for cnoidal waves are completely different from those for Stokes waves, and there are even significant differences in the variation between different cnoidal waves. 相似文献
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A two-dimensional hybrid finite element method is developed to study the scattering of water waves by an island and to calculate wave forces and moments on offshore structures. The offshore structure, which could be either semi-submerged or fully extended in the water, is assumed to be stationary. The numerical model is based on the mild-slope equation. It can be applied to both long-wave and short-wave problems. A special treatment for the problem with the semi-submerged structure is introduced. Comparisons are given with existing analytical solutions and other numerical results. The present model is shown to be an efficient and accurate method for the solution of wave refraction and diffraction problems. 相似文献
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The behavior of a highly deformable membrane to ocean waves was studied by coupling a nonlinear boundary element model of the fluid domain to a nonlinear finite element model of the membrane. The hydrodynamic loadings induced by water waves are computed assuming large body hydrodynamics and ideal fluid flow and then solving the transient diffraction/radiation problem. Either linear waves or finite amplitude waves can be assumed in the model and thus the nonlinear kinematic and dynamic free surface boundary conditions are solved iteratively. The nonlinear nature of the boundary condition requires a time domain solution. To implicitly include time in the governing field equation, Volterra's method was used. The approach is the same as the typical boundary element method for a fluid domain where the governing field equation is the starting point. The difference is that in Volterra's method the time derivative of the governing field equation becomes the starting point.The boundary element model was then coupled through an iterative process to a finite element model of membrane structures. The coupled model predicts the nonlinear interaction of nonlinear water waves with highly deformable bodies. To verify the coupled model a large scale test was conducted in the OH Hinsdale wave Research Laboratory at Oregon State University on a 3-ft-diameter fabric cylinder submerged in the wave tank. The model data verified the numerical prediction of the structure displacements and of the changes in the wave field.The boundary element model is an ideal modeling technique for modeling the fluid domain when the governing field equations is the Laplace equation. In this case the nonlinear boundary element model was coupled with a finite element model of membrane structures, but the model could have been coupled with other finite element models of more rigid structures, such as a pontoon floating breakwater. 相似文献
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数值波浪水槽是研究波浪及波浪与结构相互作用的常用工具，可在真实尺度下产生波浪，并提供流场的详细数据。然而，大部分数值波浪水槽都存在数值耗散和数值色散问题，数值耗散使波能缓慢消散，数值弥散在波传播过程中使波频移。本文在有限差分法（FDM）求解欧拉方程的基础上，提出了一种抑制数值耗散效应的简单方法，考虑阻尼项的影响，对波的传播解进行了解析求解。该方法的主要思想是在动量方程中附加一个源项，其强度由数值阻尼效应的强度决定。本文通过对规则线性波、Stokes波和不规则波的数值模拟，验证了该方法的有效性。结果表明，本文方法可有效减小数值波浪水槽中存在的数值耗散现象。 相似文献
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A numerical model is presented for the prediction of the wave field due to the diffraction of directional random waves in a harbor of arbitrary shape with partially reflecting boundaries. The water depth is assumed uniform and the method is based upon the superposition of diffraction solutions for monochromatic waves obtained by a two-dimensional boundary integral equation approach. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The present numerical model has been validated through comparisons with previous experimental data and theoretical results for both regular and random wave diffraction by offshore breakwaters and in harbors. Good agreement was obtained in all cases. Based on these comparisons it is concluded that the present numerical model is an accurate and efficient tool to predict the wave field inside a harbor or around a breakwater in many practical applications. 相似文献
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1 Introduction A vertical wall is one of the typical maritime sheltering structures in the coastal region, which is mainly subjected to wave forces. It has been a com- mon engineering assumption adopted for design pur- poses that normally incident wave fo… 相似文献
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In this paper, a numerical model is established for estimating the wave forces on a submerged horizontal circular cylinder. For predicting the wave motion, a set of two-dimensional Navier-Stokes equations is solved numerically with a finite element method. In order to track the moving non-linear wave surface boundary, the Navier-Stokes equations are discretized in a moving mesh system. After each computational time step, the mesh is modified according to the changed wave surface boundary. In order to stabilize the numerical procedure, a three-step finite element method is applied in the time integration. The water sloshing in a tank and wave propagation over a submerged bar are simulated for the first time to validate the present model. The computational results agree well with the analytical solution and the experimental data.Finally, the model is applied to the simulation of interaction between waves and a submerged horizontal circular cylinder.The effects of the KC number and the cylinder depth on the wave forces are studied. 相似文献