SPH方法在自由面问题中的应用

作为无网格粒子法,SPH法在处理大变形、自由面流动问题时具有显著的优势.介绍了SPH法的基本数值方法,并基于SPH法数值模拟了2个二维溃坝问题,将计算结果与试验数据进行了比较,结果表明:SPH法在处理自由面时具有很强的适应性.尽管水面发生了翻卷、破碎等剧烈的变化,但SPH法仍然能够较好地捕捉到这些流动现象,同时数值模拟得到的水头位置和自由面形状均能与试验结果相吻合,表明SPH法在处理自由面问题时具有较高的准确性及可靠性.     

溃坝水流模拟方法的对比分析

采用FLUENT软件与光滑粒子流体动力学法(SPH)分别对溃坝水流进行数值模拟,对比分析溃坝水流的流动形态、流速及水位变化.结果表明,两者较为一致地反映了溃坝水流的流动过程及流体的速度场,其中SPH方法能精确地捕捉自由液面,所得自由水面附近结果更为准确;FLUENT所计算的流速、水位等数据更加精确,能很好地体现水流的表面张力.分析两种方法各自的优缺点和适用性,使其在面对复杂的工程实际问题时发挥更大的作用,促进溃坝洪水数学模型的应用与发展.     

基于GPU加速的MPS方法模拟三维急弯河道溃坝流动

溃坝流动是一种灾害性的复杂流动现象,该文将GPU加速技术与MPS方法相结合,采用该课题组自主开发的MPSGPU-SJTU求解器对三维急弯细长河道中的溃坝流动问题进行了数值模拟.监测河道中轴线处自由液面水位高度与速度场分布情况表明,数值模拟结果与实验结果吻合较好.此外,该文对比了CPU与GPU的计算时间,验证了采用GPU...     

基于SPH方法的溃坝流动数值模拟

应用光滑粒子流体动力学方法对溃坝问题进行了数值模拟,在现有SPH 方法的理论基础上对密度近似方程进行了重新初始化处理,分析了密度重新初始化对溃坝流动问题的影响,并对SPH数值模拟所得到的结果与试验结果以及移动粒子半隐式方法得到的计算结果进行了比较和分析.结果表明,对密度近似方程进行重新初始化保持了流场内的质量守恒,同时整个计算域内的压力分布更加规则,SPH方法数值模拟得到的结果与实验结果和MPS方法得到的结果非常吻合,验证了改进方案及所编程序的可靠性和计算结果的准确性.     

渗流自由面数值模拟方法比较

结合最新提出的自由面适应网格法,与现行的2种固定网格法即变单元渗透系数法和初流量法进行数值模拟比较,以探讨各种方法在自由面渗流计算中的优缺点及其应用情况。试探性地选取3种固定网格方法进行系统的比较,即在精度、迭代步数、网格敏感度、初设自由面敏感性上进行多方位比较,分析各方法的灵活性、鲁棒性、数值稳定性、计算效率和可靠性...     

逐渐溃坝和瞬时溃坝的模拟研究与比较

文章针对土坝的溃坝失事,采用了逐渐溃坝和瞬时溃坝两种数学模型进行研究,在论述它们各自的机理后,结合实例验证其实用性并对其各自特点分别加以分析和比较,从而为防洪预报和决策提供科学依据     

TVD-MUSCL格式模拟二维溃坝波的演进过程

溃坝的数值模拟中存在分耗散和数值振荡的缺点,对模拟精度带来了一定的影响。本文对溃堤波的计算采用在有限体积无结构网格上建立的TVD-MUSCL格式,并引入通量限制器Roe'Superbee。模拟算例表明,此类格式能够自动捕捉激波而且能自动消除激波附近的虚假数值振荡,具有较高的计算精度。     

模拟突放水体问题的SPH方法

采用SPH方法数值模拟了二维方形水箱突放水体各时刻流动的情况,计算结果表明:模拟过程中,整个水体的密度和速度值变化不大,而压强值变化比较大。数值模拟粒子分布图可以显示出各时刻整个水体的流态、各时刻闸门开启情况及闸门对周围水体流态的影响等,闸门开启的1.460 3 s时刻,闸门左侧部分水体有相对下降缓慢的特殊流态。     

基于SPH方法的二维宽顶堰溢流数值模拟

光滑粒子水动力学方法(SPH)是一种基于纯拉格朗日思想的无网格粒子方法,在众多科学和工程领域得到了初步应用。采用SPH方法对二维宽顶堰溢流进行了数值模拟,并利用机群进行并行计算来提高计算效率,将模拟数据与试验数据进行了对比。结果表明,SPH方法可以模拟出二维宽顶堰自由出流和淹没出流时水流流态、水跌、回流区、水跃现象,计算出溢流流量、流速等水力参数,并且采用数据拟合得出与理论相符的断面流速分布图。结果表明了SPH方法可以较好模拟二维宽顶堰溢流中的流速分布以及水面曲线。     

数值模拟二维溃坝

该文应用Level Set方法研究了二维溃坝问题.用二阶投影法和高阶迎风格式求解二维Navier-Stokes方程,用CIP(cubic-Interpolated Pseudoparficle)方法求解Level-Set方程.通过数值计算得到了各个时刻溃坝运动界面的变化和相应速度的分布,该文的数值结果与相关的数值实验结果基本一致,说明该文的算法对于捕捉溃坝波的破碎和融合是实用且有效的.     

A numerical study of violent sloshing problems with modified MPS method

A numerical study on violent liquid sloshing phenomenon in a partially filled rectangular container is carried out by using moving particle semi-implicit(MPS) method. The present study deals with the implementation of five modifications all together over the original MPS method. The modifications include improved source terms for pressure Poisson equation, special approximation technique for the representation of gradient differential operator, collective action of mixed free surface particle identification boundary conditions, effecting Neumann boundary condition on solving the PPE and fixing judiciously the parting distance among particles to prevent collision. The suitability of the kernel function used in the original MPS method along with these five modifications is investigated for violent sloshing problems. The present model ensures a good agreement between numerical results with the existing experimental observations. The model is successfully applied to a partially filled tank undergoing horizontal sinusoidal excitation to compute the sloshing wave amplitudes and pressure on tank walls. The assessment of dynamic behaviour manifested in terms of base shear, overturning moment and impact pressure load exerted on tank ceiling induced by violent sloshing motion using MPS method is not reported in the open literature and has been efficiently carried out in the present study.     

Comparative study of MPS method and level-set method for sloshing flows

This paper presents a comparative study of a meshless level-set method in the simulation of sloshing flows. The numerical moving particle semi-implicit （MPS） method and a grid based schemes of the MPS and level-set methods are outlined and two violent sloshing cases are considered. The computed results are compared with the corresponding experimental data for validation. The impact pressure and the deformations of free surface induced by sloshing are comparatively analyzed, and are in good agreement with experimental ones. Results show that both the MPS and level-set methods are good tools for simulation of violent sloshing flows. However, the second pressure peaks as well as breaking and splashing of free surface by the MPS method are captured better than by the level-set method.     

堆石坝坝体沉降监测方法的对比分析

介绍了振弦式分层沉降仪和电磁式沉降仪的坝体沉降监测方法,进行了监测成果分析及与计算结果的对比分析,总结了两种监测方法在工程上的应用。     

基于SPH方法挑流水舌的数值模拟研究

以数值模拟挑流水舌的运动特性为目标,采用光滑粒子动力学方法,根据水气两相流的运动规律,建立掺气水舌的SPH数学模型,根据空气阻力的作用特性和自由表面判据,得到了空气阻力的计算关系式,提出了掺气水舌的SPH数值解法。针对桓仁水电站泄洪雾化,进行了掺气水舌的SPH数学模型实例研究,所得到的光滑粒子运动图像刻画了挑流水舌与空气的相互作用,模拟了挑流水舌的掺气过程,并得到了掺气水舌的厚度和速度随其曲线长度的变化关系。结果表明,桓仁水电站挑流水舌的外缘挑距模拟值为82.2 m,原型观测数据为80.2 m,计算误差为2.49%。掺气水舌的挑距模拟值与其原观值基本一致,证明了掺气水舌SPH数学模型模拟挑流水舌运动的有效性和可靠性。     

拱坝的抗滑稳定分析方法及相关地质问题处理措施的研究

拱坝具有极其良好的力学性能以及极为合理的经济造价,其优点众多,应用广泛;通过60多年的努力,基于大量研究与施工实践的成果,国内拱坝工程建设中的众多难题得以解决;目前,随着我国高坝大库的大量兴建,在筑坝体形设计以及施工工艺等方面积累了很多创新性的经验,为了更好地提升我国拱坝建设数量及质量,本文基于国内外已建在建各体形拱坝,对当前拱坝的稳定性分析方法进行了系统地总结和分析,基于多座代表性拱坝地质条件的详尽分析探究,指出了拱坝存在的主要地质问题,并且探索了其主要解决途径。     

Corrected SPH methods for solving shallow-water equations

The artificial viscosity in the traditional smoothed particle hydrodynamics(SPH) methodology concerns some empirical coefficients, which limits the capability of the SPH methodology. To overcome this disadvantage and further improve the accuracy of shock capturing, this paper introduces two other ways for numerical viscosity, which are the Lax-Friedrichs flux and the twoshock Riemann solver with MUSCL reconstruction to provide stability. Six SPH methods with different kinds of numerical viscosity are tested against the analytical solution for a 1-D dam break with a wet bed. The comparison shows that the Lax-Friedrichs flux with MUSCL reconstruction can capture the shock wave more accurate than other five methods. The Lax-Friedrichs flux and the artificial viscosity with MUSCL reconstruction are finally both applied to a 2-D dam-break test case in a L-shaped channel and the numerical results are compared with experimental data. It is concluded that this corrected SPH method can be used to solve shallow-water equations well.     

Effects of turbulence models on numerical simulations of wave breaking and run-up on a mild slope beach

The performance of the standard k−ε model, the high-Reynolds-number k−ω model, the 1-equation k model, and the non-friction Euler model is examined against the case of wave run-up on a mild slope. A numerical model based on N-S equations and Volume Of Fluids (VOF) method is employed. Comparisons of elevation, velocity and shear stress are made among the four turbulence models against experimental data of wave run-up on a mild slope beach. It is found that before wave breaking on the slope, the outputs of the four different turbulence models agree reasonably well with each other. This suggests that during the run-up process the turbulence effect is negligible before wave breaking. Moreover, in the wave breaking zone, both the standard k−ε model and the high-Reynolds-number k−ω model predict the mean velocity field quite well, but generally under-predict the velocity and turbulent kinetic energy using wall functions on the solid slope surface.

     

浆砌块石重力坝弹性模量两种反演方法对比研究

深圳赤坳水库的大坝为浆砌块石重力坝,经过多年运行,材料参数已经发生变化。为反演大坝目前的弹性模量,首次采用支持向量机和粒子群反演方法进行对比研究,利用实测数据进行大坝弹性模量反演。两种反演方法结果接近,相互验证说明反演结果是正确的,同时也说明了上述两种方法在浆砌块石重力坝的反演分析工作中的可行性。     

带闸墩溢流坝控泄工况二维与三维数值模拟

引入水气两相流模型,利用k-ε紊流模型模拟银盘水电站带闸墩坝面上的复杂紊流流场,采用非结构网格来处理复杂的边界形状,采用有限体积法进行迭代求解。通过二维和三维模拟计算得到坝面水流的水面线位置、坝面压力分布以及流线分布情况,并将二维和三维数值模拟结果与物理模型试验结果进行对比分析。结果表明,与二维计算结果相比,三维计算结果与物理模型试验结果吻合程度更高,特别是对进口压力与水跃发生点的模拟,三维模拟更加准确。     

Numerical simulations of multi-layer-liquid sloshing by multiphase MPS method

In this paper,a multiphase moving particle semi-implicit (MPS) method is developed by introduction of various multiphase models into the original MPS method for...