复杂结构数值模拟的精细分析

针对用户对模型数值模拟要求越来越高的问题,对于用户关心的区域(局部复杂结构区域),采取足够细的网格来得到满意的结果,对于这些区域之外的部分,则采取密度适中的网格来处理. 以连杆螺栓啮合区域的精细分析为例,结合ANSYS子模型技术的功能特点,进行复杂结构数值模拟的精细分析. 结果表明该技术为复杂结构中重点关注区域的应力精确分析提供1种有效方法.     

突扩管中磁性流体二维流动的模拟

数学模拟可以用来预测流体在突扩管中的流动并更好使用和优化产品制造。使用Herschel-Bulkley(H-B)作为本构方程。在没有磁场的条件下,通过改变参数,我们获得了不同磁性流体的流动过程并分析了回流区长度与参数之间的关系。     

出口结构对循环流化床提升管二维流动模拟的影响

实验表明,出口结构对循环流化床提升管内截面平均空隙率等流动分布有明显影响。目前对提升管出口的二维模拟研究比较多,但大多忽略出口结构对流动行为的影响。本文对内径76mm、高10.2 m的循环床提升管进行了二维模拟,研究不同出口结构对提升管内流动的影响。结果表明,出口结构对提升管出口处的固相循环通量、出口附近轴向浓度分布有明显影响:在侧边出口条件下,径向浓度分布结果呈现非对称分布,固相速度径向分布在出口附近有明显减小。模拟结果与实验值对比也印证了上述结论。     

二维L-系统的推广及在植物模拟中的应用

弯曲枝条的模拟是植物模拟的重要组成部分,L-系统是植物模拟的重要方法之一。如果用L-系统模拟弯曲的枝条,则需要大量的产生式。通过在产生式中增加弯曲符号以及描述弯曲程度的曲率函数得到了函数L-系统。利用函数L-系统模拟植物,在不改变产生式个数的情况下,通过调整曲率函数能够绘制出相同拓扑结构,但整体形态差异较大的植物;利用函数L-系统模拟具有弯曲枝条的植物,产生式简洁,同时在编程时,容易控制枝条的长度。     

大中型水利枢纽工程精细化管理平台的构建

为满足新时代对现代大中型水利工程管理提出的精细化、智能化的要求,基于数据同步组件搭建数据汇集服务,实现控制区多源实时、历史数据的整合与共享,采用B/S技术路线,通过数据级权限管理、可视化表单编辑器、工作流管理等关键技术开发出精细化管理平台,实现管理驾驶舱、任务管理、设备管理、调度运行、日常检查、水政管理、安全管理、项目...     

输水工程取水头部水流特性三维数值模拟研究

首先阐述三维紊流的计算方法,针对输水工程进水口水流特性,采用标准k-ε模型对三维水流运动进行计算,选取VOF法对自由表面进行处理,利用有限体积法对计算区域进行离散化,并采用无滑移的固壁边界条件,模拟进水口水流的复杂流动状态,并将数值模拟的结果与试验资料进行详细比对,验证数学模型的可靠性,在进水口工程设计研究中有较大参考价值。     

Reconstruction of 2D river beds by appropriate interpolation of 1D cross-sectional information for flood simulation

The 2D numerical simulation of river flow requires a large amount of topographic data to build an accurate Digital Terrain Model which must cover the main river channel and the area likely to be flooded. DTMs for large floodplains are often generated by LiDAR flights. However, it is often impossible to obtain LiDAR data of permanently inundated river beds. These areas are often surveyed and discrete cross-sections of the river channel are obtained. This work presents an algorithm to generate the missing information for the areas between cross-sections. The algorithm allows to generate a river bed which preserves important morphological features such as meanders and thalweg trajectory. Two benchmark cases are studied: a synthetic river-floodplain system and a real case application on a reach of the Ebro river in Spain. The cases are analyzed from a geometry and hydrodynamics perspective by performing 2D simulations with good results.     

流量装置流量稳定性数值仿真评价方法研究

为了提高装置流量稳定性,提出基于计算流体动力学（ CFD）仿真,采用轴向动量数KU、旋流数KV 和不对称数KA ,分析管路不同截面位置的流场速度特征,利用多个截面位置的特征参数变化,评价装置管路的流量稳定性。对新建水装置流量稳定性进行数值仿真分析与实验测试,得出一致性结论。该方法可以在装置设计阶段,对流量稳定性进行评价,从而优化管路结构,提高装置流量稳定性。     

圆柱绕流的二维数值模拟和尾迹分析

为指导机械设计中参数和布局的选择,研究固定在水流中的圆柱结构件的受力情况和流场分布．利用FLUENT中的三种湍流模型对雷诺数为3900的圆柱绕流进行二维数值模拟并进行对比,得到升力因数、阻力因数、分离角、斯特劳哈尔数和涡街尺寸等参数的模拟结果,与参考文献中的实验结果对比验证二维模拟的预测精度．RKE（Realizable k-ε）和雷诺应力模型（Reynolds Stress Model,RSM）均能在此雷诺数下得出接近实验结果的流场,RSM模型使用POWER LAW离散格式的结果优于QUICK格式．与三维模拟的对比表明二维模拟适合在设计初期的快速估算,能够快速得到合适精度的模拟结果．     

Superposition of local zoom models and simultaneous calibration for 1D–2D shallow water flows

We address the problem of coupling 2D shallow water equations with 1D shallow water equations (St-Venant equations), as applied to river-floodplain flows. Mathematical coupling conditions are derived classicaly from the 3D Navier–Stokes equations by integrating over the vertical wet section, when overflowing occurs. It leads to extra source terms in the 1D equations. Next we assume to be in a variational data assimilation context, then the optimal control process allows to couple both models and assimilate data simultaneously (Joint Assimilation Coupling algorithms). Two different versions of JAC algorithms are presented and compared. In a numerical test case, we superimpose the local 2D model on the 1D global model. The results show the efficiency of the present simultaneous superposition–assimilation approach.     

Comfort design and optimization of direct expansion multi-connected radiant air conditioning based on 3D flow field simulation

The air conditioning method based on radiation heat exchange has the characteristics of small vertical temperature gradient, high thermal comfort and energy saving, and has become a hot spot of attention. The Fluent numerical simulation, the experiment in this paper studies the direct expansion multi-line radiant air conditioner under the artificially simulated climate environment in winter heating, summer cooling and dehumidification. The temperature difference of the radiation + fresh air mode at the same time indoors under heating conditions is less than 2.5 °C, and the time to reach the indoor set temperature of 24 °C is about 2–3 h. Under cooling conditions, the temperature difference of the radiation + fresh air mode at the same time in the room is about 0.5–2 °C, and the time to reach the indoor set temperature of 26 °C is about 1–3 h. In the fresh air mode, the indoor temperature difference and response time at the same time are slightly larger than the radiation + fresh air mode. The freezing and dehumidification effect of fresh air is obvious, the moisture content of dehumidifying fresh air is between 6.3 and 10.5 g/kg, and the dehumidification efficiency can reach 50%. Under the same artificial simulated climate environment, the consumption of the three modes is not much different. When the outdoor temperature in heating conditions is higher than 9 °C, the fresh air mode can get better, and the radiation + fresh air mode can achieve better comfort when running indoors under various conditions.     

高速公路不停车收费系统仿真研究及应用*

选择沪宁高速公路的无锡东收费站作为仿真对象,对其交通流特性作了调查和分析,为仿真参数的选取和仿真程序的编制提供了依据。给出了仿真程序的总体框架及数据结构,并介绍了关键类的主要成员变量和成员函数。利用仿真程序ETSP对一条、两条和三条ETC专用车道情况下的收费站平均延误进行仿真,绘制出低、中、高三个代表性交通量下的ETC使用率对收费站整体服务水平的影响图,分析了ETC专用车道数、ETC使用率和收费站通行能力三者之间的关系,为ETC的实施提供依据。     

高速公路不停车收费系统仿真研究及应用

选择沪宁高速公路的无锡东收费站作为仿真对象,对其交通流特性作了调查和分析,为仿真参数的选取和仿真程序的编制提供了依据。给出了仿真程序的总体框架及数据结构,并介绍了关键类的主要成员变量和成员函数。利用仿真程序ETSP对一条、两条和三条ETC专用车道情况下的收费站平均延误进行仿真,绘制出低、中、高三个代表性交通量下的ETC使用率对收费站整体服务水平的影响图,分析了ETC专用车道数、ETC使用率和收费站通行能力三者之间的关系,为ETC的实施提供依据。     

原油含水率测量多因素影响的数值模拟与实验研究

基于介电常数法测量原油含水率,往往受油水两相流态、温度、矿化度、非线性特性等多因素的影响.因此,设计一套基于多传感器的油水两相流实验室模拟系统,利用理论计算结合数值模拟的方法,研究含水率、温度、矿化度、油水介电常数、含水测最传感器输出之间的数学关系及影响规律,对提高测量含水率的精度提供了有力的理论和实验依据.