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1.
《水动力学研究与进展(B辑)》2016,(6)
We present a Cartesian grid method for numerical simulation of strongly nonlinear phenomena of ship-wave interactions. The Constraint Interpolation Profile(CIP) method is applied to the flow solver, which can efficiently increase the discretization accuracy on the moving boundaries for the Cartesian grid method. Tangent of Hyperbola for Interface Capturing(THINC) is implemented as an interface capturing scheme for free surface calculation. An improved immersed boundary method is developed to treat moving bodies with complex-shaped geometries. In this paper, the main features and some recent improvements of the Cartesian grid method are described and several numerical simulation results are presented to discuss its performance. 相似文献
2.
BAI Wei 《水动力学研究与进展(B辑)》2013,25(6):829-838
Fixed and forced moving circular cylinders in turbulent flows are studied by using the Large Eddy Simulation (LES) and two-equation based Detached Eddy Simulation (DES) turbulence models. The Cartesian cut cell approach is adopted to track the body surface across a stationary background grid covering the whole computational domain. A cell-centered finite volume method of second-order accuracy in both time and space is developed to solve the flow field in fluid cells, which is also modified accordingly in cut cells and merged cells. In order to compare different turbulence models, the current flow past a fixed circular cylinder at a moderate Reynolds number, Re = 3 900, is tested first. The model is also applied to the simulation of a forced oscillating circular cylinder in the turbulent flow, and the influences of different oscillation amplitudes, frequencies and free stream velocities are discussed. The numerical results indicate that the present numerical model based on the Cartesian cut cell approach is capable of solving the turbulent flow around a body undergoing motions, which is a foundation for the possible future study on wake induced oscillation and vortex induced vibration. 相似文献
3.
Aiming at resolving the grid problems caused by the inconsistent resolution requirements when simulating overland flows using the 2D shallow water equations, a novel grid generation method based on multi-resolution data fusion is developed in this work. This method is able to not only reduce the computational burden associated with uniform structured grids but also ensure the simulation accuracy of the hydrodynamic model by reproducing the so-called small-scale effect. The efficiency of the method is assessed using different cases. Theoretical and laboratory cases demonstrate that fused non-uniform structured grids can reproduce hydrographs without appreciable accuracy losses. In addition, a high simulation accuracy (NRMSE ≤ 10.40 %, R2 ≥ 0.87) is achieved in the simulation of a real flood event. The performance of this method is very promising in terms of the large-scale flood simulation accuracy, and it significantly reduces the data requirements and computational burden with globally fine uniform grids. 相似文献
4.
A multispecies, two- and three-dimensional model was developed, based on a previously published planar biofilm model, and the biochemical structure of the ADM1. Several soluble substrates diffuse and react in the granule. Local pH is calculated from acid-base equilibria and charge balance. The model uses individual-based representation of biomass particles within the granule (biofilm), and describes spreading by an iterative pushing technique. The overall computational domain consists of one granule, and is divided into a grid with Cartesian coordinates. The number of grid elements does not limit the number of biomass particles, and it is not necessary to use grid-spreading techniques, such as cellular automata, which result in Cartesian artefacts. The model represents both microscopic and macroscopic features in granule structure, previously observed using in-situ molecular techniques, and can be effectively used to interpret these results. 相似文献
5.
The parallel computing algorithm for a nonhydrostatic model on one or multiple Graphic Processing Units (GPUs) for the simulation of internal solitary waves is presented and discussed. The computational efficiency of the GPU scheme is analyzed by a series of numerical experiments, including an ideal case and the field scale simulations, performed on the workstation and the super-computer system. The calculated results show that the speedup of the developed GPU-based parallel computing scheme, compared to the implementation on a single CPU core, increases with the number of computational grid cells, and the speedup can increase quasilinearly with respect to the number of involved GPUs for the problem with relatively large number of grid cells within 32 GPUs. 相似文献
6.
GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW 总被引:8,自引:0,他引:8
Zhao Ming deng Li Yi tian Department of River Engineering Wuhan University Wuhan China 《水动力学研究与进展(B辑)》2001,(2)
1 . INTRODUCTIONInnaturalriver,theshapesofboundariesandsec tionsareoftenirregular ,whichisadifficultproblemfornumericalsimulation .Tosolvethisproblem ,acoordi natetransformationmethodisoftenusedtotransformtheirregularregioninthephysicalplane(X ,Y)totheregula… 相似文献
7.
NUMERICAL SOLUTION FOR TIDAL FLOW IN OPENING CHANNEL USING COMBINED MACCORMACK-FINITE ANALYSIS METHOD 总被引:1,自引:1,他引:0
WU Zhao-chun 《水动力学研究与进展(B辑)》2009,21(4):505-511
A new numerical scheme for solving the tidal flow in an opening channel using the advective-diffusion shallow-water equations as the governing equations is proposed based on the combination of the MacCormack and the finite analysis methods. In the present scheme, the finite analysis method is used to discretize the momentum equation and the MacCormack technique is used to discretize the continuity equation in a single grid system. The matrix of the discretized momentum equation is characterized by predominantly main diagonal elements, which ensures favorable convergence and stability for the numerical simulation by the combined method. To verify the present method, hydraulics simulation is carried out for a section down mainstream of the Huangpu River. The computational results agree with the measured data. By use of orthogonal curvilinear coordinate system, the methods can be easily extended to the numerical simulation of the tidal flow in a tortuous channel. 相似文献
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9.
A new method is presented for the water impact simulation, in which the air-water two phase flow is solved using the pressure-based computational fluid dynamics method. Theoretically, the air effects can be taken into account in the water structure interaction. The key point of this method is the air-water interface capture, which is treated as a physical discontinuity and can be captured by a well-designed high order scheme. According to a normalized variable diagram, a high order discrete scheme on unstructured grids is realised, so a numerical method for the free surface flow on a fixed grid can be established. This method is implemented using an in-house code, the General Transport Equation Analyzer, which is an unstructured grid finite volume solver. The method is verified with the wedge water and structure interaction problem. 相似文献
10.
Water Supply Systems (WSS) are large consumers of energy mainly used in pumping stations and treatment plants. Therefore,
the improvement of energy efficiency is a major priority for water utilities. The current research work presents a new methodology
and a computational algorithm based on renewable energy concepts, hydraulic system behaviour, pressure control and neural
networks for the determination of the best hybrid energy configuration to be applied in a typical water supply system. The
Artificial Neural Network (ANN) created to determine the best hybrid system uses scenarios with only grid supply, grid combined
with hydro turbine, with wind turbine and mutual solutions with hydro and wind turbine. The ANN is trained based on values
obtained from a configuration and economical simulator model (CES), as well as from a hydraulic and power simulator model
(HPS). The results obtained show this ANN advanced computational model is useful for decision support solutions in the plan
of sustainable hybrid energy systems that can be applied in water supply systems or other existent hydro systems allowing
the improvement of the global energy efficiency. A real case study is analysed to determine the best sustainable hybrid energy
solution in a small WSS of Portugal. 相似文献
11.
深入认识大型江湖系统水动力特性,需要使用平面二维数学模型代替传统一维数学模型开展模拟和研究。当以高分辨率计算网格作为前提时,大型江湖系统二维水动力模型“计算精度与效率”的矛盾则转化为计算效率瓶颈。以荆江-洞庭湖系统为背景(剖分为32.8万个四边形单元,最小网格尺度约50 m),选用MIKE21模型和一种半隐式欧拉-拉格朗日模型,开展大型江湖系统显式、隐式水动力模型性能的比较研究,探讨大型江湖系统高分辨率二维模型的可实用性。研究结果表明:显式模型稳定性较差,允许的最大时间步长为0.8 s;隐式模型稳定性好,时间步长可达60 s以上;在常规16核工作站的效率测试结果表明,显式模型具有良好的可并行性,加速比随核心数量基本呈现线性变化;隐式模型(使用预测-校正分块并行计算方法)亦可取得非常大的加速比,在16核心并行条件下加速比Sp可达11.1;模拟荆江-洞庭湖系统1年的非恒定流过程,显式、隐式模型的耗时分别为411、10.76 h(16核),后者计算效率是前者的38.2倍,可满足大型江湖系统整体高分辨率平面二维水动力模拟的实用性要求。 相似文献
12.
游荡型河流的平面二维水沙数学模型 总被引:9,自引:1,他引:9
为使数学模型能模拟游荡性河流因水流弯曲、分汊等导致的环流输沙作用,本文首先在悬移质泥沙对流扩散方程中增加了横向输沙项,然后引入适合游荡型河流的塌岸模式及局部动网格技术和网格融合技术,解决了河岸变形模拟和河道整治工程导致网格再生、床沙级配变化模拟等关键性难题,开发出可模拟游荡性河流河床演变且可反映河道整治工程作用的平面二维水沙数学模型。最后,以黄河下游柳园口—夹河滩河段为例,应用本文模型对游荡型河流河势变化进行了数值模拟,结果表明本模型能够真实地模拟出游荡型河流独特的河床演变过程。 相似文献
13.
RECENTPROGRESSININCOMPRESSIBLEREYNOLDSAVERAGEDNAVIER-STOKESSOLVERS¥C.H.Sung;T.T.Huang(DavidTaylorModelBasin,CD/NSWCBethesda,M... 相似文献
14.
在洪水波演进过程中,地形是主要影响因素之一,根据计算区域内地形变化自动调整网格分布,可以使计算模型和计算结果能更加细致和精确地反映客观地形地貌。本文分析了江河洪水演进模拟中网格自动生成方面的需求,探讨了洪水模拟中两类地形自适应问题:突变地形和缓变地形。对于如堤防等阻水建筑物,概括为一种地形突变,网格自动生成时此类地形的自适应可以转化为边界自适应问题,因为此类地形突变一般均能以连续折线来表示。而对于缓变地形,本文提出了通过曲面样条函数拟合,形成计算区域内连续光滑的地形曲面,从而通过各点高程梯度来控制网格尺寸,实现网格生成过程中的地形自适应,即在地势平坦区域加大网格尺寸,而在地势变化剧烈的区域,加密网格。 相似文献
15.
一种小型轴流式水轮机的数值模拟 总被引:1,自引:0,他引:1
为了有效地利用海洋能源,为某些水下系统提供便捷的电力供应,设计了一种小型的轴流式水轮机。借助 CFX-TurboGrid生成网格,采用CFX-TASCflow软件平台,对叶片进行数值计算,验证其性能。对水轮机一个流道进行不同工况下的计算,对计算结果的分析得出水轮机的性能曲线;选择几种工况的试验数据,并与理论计算结果相比较,结果较吻合;修改计算模型,可以得到更符合要求的水轮机。 相似文献
16.
基于一套新颖高效自主开发的大涡模拟CFD平台,强调采用空间固定的笛卡尔网格下控制方程及无需边界拟合的切削网格法,通过构建两相流质量力数学模型,来精确有效描述单个运动物体对流场影响.该平台另一特点是设计新颖VOF算法,并开发一类基于尖锐界面法理念的模拟气液两相流模型.数值计算包含强非线性自由面的典型实例如出入水砰击、滑坡涌浪、液舱晃荡及风浪与结构物的相互作用,包括网格细化及相关试验的比较.结果表明:所提出的描述运动物体影响的两相流质量力模型,用于模拟运动物体诱导的流固耦合问题是可行及有效的. 相似文献
17.
文章以在几内亚设计220 kV变电站的地网设计方案为例应用CDEGS软件进行仿真分析,校验传统设计法是否能满足安全要求,并提出优化方案,旨在为变电站的地网设计提供参考。 相似文献
18.
求解水动力弥散方程的多单元均衡法 总被引:2,自引:0,他引:2
黄军旗 《水动力学研究与进展(A辑)》1990,5(4):19-26
本文给出一种多孔介质溶质输运方程的多单元均衡解法。该方法基于多孔介质溶质输运理论和物质守衡原理,在三角形单元的局部座标系中对溶质传输的物质流强度方程进行差分,直接形成未知函数离散后的系数矩阵。方法简易,形式简单,物理意义直观,实用方便。 相似文献
19.
离散裂缝网络模型主要从裂缝的几何形状以及流动机理上对裂缝进行表征和描述,可以比较精确地描述裂缝特征及油藏的非均质性。该文结合油藏边界及裂缝的真实分布状态,将油藏划分为若干子区域,在每个子区域上布网格节点进行Delaunary三角剖分与Vornoni网格剖分,得到了PEBI网格。为了满足质量守恒,利用有限体积法进行了求解,对网格域和计算域之间的误差进行了修正。结合离散裂缝的数学模型及传导率计算法则,实现了高精度的离散裂缝油藏数值模拟,研究了大裂缝的分布、长短、与注采井的贯穿状况等因素对水驱油的推进方向、速度、见水时间、采出程度的影响规律。结果表明PEBI网格能准确地表征裂缝特征,再现裂缝的分布,正确地模拟裂缝影响下的水驱开发规律。 相似文献