共查询到20条相似文献，搜索用时 125 毫秒
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建立具有色散性的水平二维非线性波浪方程,方程的非线性近似到了三阶。方程以波面升高和自由表面速度势表达的微分-积分型数学方程,给出方程的数值求解方法和算例,对方程积分项的处理给出了计算方法。计算结果与Boussinesq方程模型和缓坡方程模型的对应计算结果进行了对比。 相似文献
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为了提高粒子法即移动粒子半隐式法(Moving Particle Semi-implicit method, MPS法)中自由表面粒子的识别精度,降低由粒子误判引起的非物理压力振荡,对MPS法的自由表面识别方法进行了改进。在原始自由表面判别标准的基础上增加辅助判别条件,提出2种新的自由表面判别法即压力判别法和填充率判别法。利用对静水问题和溃坝流问题的模拟计算,对比分析选用不同自由表面判别法得到的数值计算结果,揭示粒子识别精度对压力计算的重要影响。研究结果表明:新提出的压力判别法和填充率判别法可以有效地提高自由表面粒子的识别精度,减轻压力计算中的非物理压力振荡现象,从而提高压力计算的稳定性以及整体数值计算的模拟精度。 相似文献
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虚拟速度—临界角谱是地震折射波虚拟射线理论的应用之一。根据共始点或共折射点记录的相似性,利用第一虚拟时距曲线方程,对时距曲线进行扫描计算,可以制作共始点谱和共折射点谱。 文中,通过实际介质模型的计算机试算结果,对该方法作了验证。 相似文献
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从三维边界元方法出发,基于Wagner的自由液面抬升理论,采用数值仿真的方法研究了圆球入水的问题。通过数值模拟与轴对称体入水试验结果的正确性及适用性进行验证的基础上,并分析了不同半径的球体在不同速度下的入水总体受力和表面压力的变化规律。计算结果表明随着球体半径和入水速度的增加,峰值压力迅速增加,受力峰值与球体半径的平方和入水速度平方成正比关系;球体表面压力系数的分布计算结果表明,在测试点与水开始接触时压力系数最大,然后迅速减小;压力系数和入水速度无关,但和入水深度相关。 相似文献
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本文用有限元法配合时步处理来求解三维非线性水波的绕射问题,自由表面条件和物面条件都满足到二阶,采用人工阻尼区来吸收反射波,流场内的速度势通过求解有限元方程得到。对垂直圆柱体的绕射问题进行了计算,得到了自由表面波高时间历程和圆柱所受到的波浪力,计算结果和有关文献的理论计算结果进行了比较。 相似文献
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基于紊流随机理论的航槽三维流动数学模型 总被引：1，自引：0，他引：1
根据窦国仁的紊流随机理论，建立了一种模拟河口海岸水域中航槽三维流动的数学模型。采用控制体积法导出三维偏微分方程的离散格式；将水压力分解为动水压力和静水压力，用Patankar和Spalding提出的压力校正法求解动水压力，通过求解水位控制方程来得到自由表面；紊流模型采用安国仁提出的紊流随机理论，克服了k—ε模型中采用各向同性紊动粘滞系数的不足，而k—ε模型可作为紊流随机理论的一个特例。该模型计算了各种不同挖深比，各种航槽与水流交角的航槽流速分布，利用该模型计算得到的挖槽中的流速分布与水槽及水池试验资料相吻合。利用该模型可为开敞水域中开挖航槽的选择提供依据。 相似文献
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In this paper, a numerical model is established. A modified N-S equation is used as a control equation for the wave field and porous flow area. The control equations are discreted and solved by the finite difference method. The free surface is tracked by the VOF method. The pressure field and velocity field of the whole flow area are solved by the reiterative iteration method. Finally, compared with the physical model test results of wave flume, the numerical model established in the present study is validated. 相似文献
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A vertical two-dimensional numerical model has been applied to solving the Reynolds Averaged Navier- Stokes （RANS} equations in the simulation of current and wave propagation through vegetated and non- vegetated waters. The k-e model is used for turbulence closure of RANS equations. The effect of vegeta- tion is simulated by adding the drag force of vegetation in the flow momentum equations and turbulence model. To solve the modified N-S equations, the finite difference method is used with the staggered grid system to solver equations. The Youngs＇ fractional volume of fluid （VOF） is applied tracking the free sur- face with second-order accuracy. The model has been tested by simulating dam break wave, pure current with vegetation, solitary wave runup on vegetated and non-vegetated channel, regular and random waves over a vegetated field. The model reasonably well reproduces these experimental observations, the model- ing approach presented herein should be useful in simulating nearshore processes in coastal domains with vegetation effects. 相似文献
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Investigating the wave field near structures in coastal and offshore engineering is of increasing significance. In the present study, simulation is done of the wave profile and flow field for waves propagating over submerged bars, using PLIC-VOF （Pieeewise Linear Interface Construction） to trace the free surface of wave and finite difference method to solve vertical 2D Navier-Stokes （N-S） equations. A comparison of the numerical results for two kinds of submerged bars with the experimental ones shows that the PLIC-VOF model used in this study is effective and can compute the wave field precisely. 相似文献
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稳恒水波的Fourier近似解研究 总被引：1，自引：0，他引：1
A computational method for steady water waves is presented on the basis of potential theory in the physical plane with spatial variables as independent quantities. The finite Fourier series are applied to approximating the free surface and potential function. A set of nonlinear algebraic equations for the Fourier coefficients are derived from the free surface kinetic and dynamic boundary conditions. These algebraic equations are numerically solved through Newton＇s iterative method, and the iterative stability is further improved by a relaxation technology. The integral properties of steady water waves are numerically analyzed, showing that （1） the set-up and the set-down are both non-monotonic quantities with the wave steepness, and （2） the Fourier spectrum of the free surface is broader than that of the potential function. The latter further leads us to explore a modification for the present method by approximating the free surface and potential function through different Fourier series, with the truncation of the former higher than that of the latter. Numerical tests show that this modification is effective, and can notably reduce the errors of the free surface boundary conditions. 相似文献
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A Vertical Two-Dimensional Model to Simulate Tidal Hydrodynamics in A Branched Estuary 总被引：1，自引：1，他引：1
A vertical (laterally averaged) two-dimensional hydrodynamic model is developed for tides, tidal current, and salinity in a branched estuarine system. The goveming equations are solved with the hydrostatic pressure distribution assumption and the Boussinesq approximation. An explicit scheme is employed to solve the continuity equations. The momentum and mass balance equations are solved implicitly in the Cartesian coordinate system. The tributaries are govemed by the same dynamic equations. A control volume at the junctions is designed to conserve mass and volume transport in the finite difference schemes, based on the physical principle of continuum medium of fluid. Predictions by the developed model are compared with the analytic solutions of steady wind-driven circulatory flow and tidal flow. The model results for the velocities and water surface elevations coincide with analytic results. The model is then applied to the Tanshui River estuarine system. Detailed model calibration and verification have been conducted with measured water surface elevations,tidal current, and salinity distributions. The overall performance of the model is in qualitative agreement with the available field data. The calibrated and verified numerical model has been used to quantify the tidal prism and flushing rate in the Tanshui River-Tahan Stream, Hsintien Stream, and Keelung River. 相似文献
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A numerical time simulation method is described to solve fluid flow problems including unsteady free surface motion. The method is based on potential flow theory. At every time step, the problem is solved using a boundary integral formulation of the fluid domain. The linearized free surface conditions are integrated in time and the solution is marched forward. Computational results simulating the free surface motion for the cases of a linear progressive wave, wave propagating into a region of calm water and the wave maker motion are presented. Comparison with theoretical results demonstrate the feasibility of the proposed simulation scheme. 相似文献
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A new coupling model of wave interaction with porous medium is established in which the wave field solver is based on the two dimensional Reynolds Averaged Navier-Stokes (RANS) equations with a kε closure. Incident waves, which could be linear waves, cnoidal waves or solitary waves, are produced by a piston-type wave maker in the computational domain and the free surface is traced through the Piecewise Linear Interface Construction-Volume of Fluid (PLIC-VOF) method. Nonlinear Forchheimer equations are adopted to calculate the flow field within the porous media. By introducing a velocity–pressure correction equation, the wave field and the porous flow field are highly and efficiently coupled. The two fields are solved simultaneously and no boundary condition is needed at the interface of the internal porous flow and the external wave. The newly developed numerical model is used to simulate wave interaction with porous seabed and the numerical results agree well with the experimental data. The additional numerical tests are also conducted to study the effects of seabed thickness, porosity and permeability coefficient on wave damping and the pore water pressure responses. 相似文献
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P.D. Scarlatos 《Coastal Engineering》1982,6(1):27-45
The Saint-Venant system of partial differential equations is solved by a pure finite-element method, in which integrations in both space and time are performed by utilizing Galerkin's procedure. With a special treatment of the non-linear terms, the problem is finally reduced to a linear system of algebraic equations that is solved by the conjugate gradient algorithm. This implicit scheme is proved, by numerical experiments, to be unconditionally stable. The reliability of the method is investigated by comparison of the numerical results with experimental data. Also the accuracy of the model is tested against analytical solutions for simplified cases of the unsteady free surface flow equations. 相似文献
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建立了波浪与大孔隙多孔介质相互作用的耦合数学模型,波浪域的控制方程为雷诺时均方程和k-ε紊流模型。对于计算域的入射波采用推板式造波,它可以是线性波、椭圆余弦波和孤立波。采用PLIC-VOF法追踪波浪自由表面。对于多孔介质内的孔隙流场采用非线性Forchheimer方程,两区域共享连续方程,最后导出的波浪域与孔隙流域的压力修正方程具有完全相同的形式,利用这个方程能够同时而不是分别求解波浪场和孔隙流场,避免了在内部边界上给定匹配条件,实现了波浪场与孔隙流场的同步耦合。波浪与粗颗粒海床、平底床面上抛石潜堤及斜坡上抛石潜堤相互作用的验证计算结果表明该模型可用于研究波浪与大孔隙多孔介质相互作用的问题。 相似文献
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A numerical model is developed by combining a porous flow model and a two-phase flow model to simulate wave transformation in porous structure and hydraulic performances of a composite type low-crest seawall. The structure consists of a wide submerged reef, a porous terrace at the top and an impermeable rear wall. The porous flow model is based on the extended Navier-Stokes equations for wave motion in porous media and k−ε turbulence equations. The two-phase flow model combines the water domain with the air zone of finite thickness above water surface. A unique solution domain is established by satisfying kinematic boundary condition at the interface of air and water. The free surface advection of water wave is modeled by the volume of fluid method with newly developed fluid advection algorithm. Comparison of computed and measured wave properties shows reasonably good agreement. The influence of terrace width and structure porosity is investigated based on numerical results. It is concluded that there exist optimum value of terrace width and porosity that can maximize hydraulic performances. The velocity distributions inside and in front of the structure are also investigated. 相似文献