Fluent软件的技术特点及其在暖通空调领域的应用

文章介绍了计算流体动力学(CFD)技术的一般结构,着重阐述了商用CFD软件中Fluent软件的主要特点,并举例说明Fluent在暖通空调领域中的应用,以传统壁挂式空调环境下的气流组织为例,用该软件进行数值模拟,分析室内温度场的变化情况.     

基于Fluent二次开发地铁通风系统日志文件

空调设计工程师应用Fluent软件对地铁空调通风系统进行数值分析仿真过程中遇到了诸多问题,如：重复性工作多、对使用者的流体专业知识要求过高等,通过Visual Basic高级编程语言编译仿真平台,调用Journal参数化日志文件,可以解决此类问题.参数化日志文件的应用是对Fluent软件进行二次开发的重要方法,不仅能够提高工作效率而且降低使用者门槛.本文研究内容：1)重点研究了Gambit与Fluent软件的命令流文件(Journal日志文件)的编写方法.2)Gambit与Fluent软件能够根据输入的参数对车体模型自动参数化建模、自动进行数值仿真计算并保存后处理结果.3)Journal日志文件在计算过程中能灵活地实现CFD分析中的相关功能,并且能够对计算结果与实验数据进行对比.因此, Fluent二次开发在实际工程上有着非常广阔的应用前景.     

化学链反应数值模拟的国内外研究现状

阐述了4种常用的数值模拟软件(COMSOL Multiphysics,Aspen Plus,ANSYS Fluent和MATLAB)在化学链中的应用,总结出化学链中常用的动力学模型,数值模拟常规的设计需要考虑的因素以及操作步骤。通过CNKI和Web of science数据库采用计量学的方法对四大软件的应用分析,总结每个软件在化学链技术中的优劣指提出COMSOL Multiphysics作为化学链燃烧技术数值模拟的主导软件的趋势。     

基于Fluent的动态旋流器流场计算机模拟仿真

Fluent软件是一款集流场、热传质、燃烧以及化学反应于一体的商业CFD 软件. 针对动态旋流器流场的复杂多变性, 以Total型动态旋流分离器为例, 在Gambit软件中简化并建立了物理模型, 通过fluent软件对其速度场进行计算机模拟仿真, 得出了柱坐标系统下, 切向速度、轴向速度和径向速度三个速度分量云图, 通过研究发现, 基于Fluent的动态旋流器流场计算机模拟仿真可以有效地解决复杂流动问题, 为动态旋流器工艺设计和性能优化提供可靠的依据, 且节省开发费用, 缩短设计周期.     

基于FLUENT的综掘面风幕集尘除尘系统数值模拟

针对目前井下巷道内的粉尘防治难的情况,研发了一种新型风幕风机。应用计算流体力学Fluent软件对综掘工作面的风幕集尘除尘系统进行数值模拟,通过模拟可以得到风幕风机的风幕形成过程,以及粉尘颗粒轨迹。模拟结果说明了风幕集尘除尘系统防治粉尘可行。     

水力溢流分级机内碳化硅微粉体积分率时空分布的模拟

为了进一步理解水力溢流分级机的分级原理,采用双流体模型中的Mixture模型,应用Fluent软件模拟了直径1.8 m的水力溢流分级机分级碳化硅微粉的过程,研究了不同粒径的颗粒在分级机内的体积分率时空分布规律,探讨了沉降颗粒和溢流颗粒在不同分级时间下的粒径分布情况.模拟结果表明:粒径＜3.36 μm的细颗粒和粒径在3....     

基于Fluent的全机数值模拟及并行计算

利用CFD商用软件Fluent对亚声速飞行飞机的三维绕流流场进行了数值模拟以及并行计算,得到了飞机附近的流场,实现了此软件在高性能并行计算机上的并行;并且通过对不同数量网格在不同结点数目机群上的计算结果进行分析比较,验证了此商用软件在并行平台上应用的有效性,也为进行大规模科学工程计算提供了技术参照。     

基于FLUENT的综掘面风幕集尘除尘系统参数研究

针对井下综掘面粉尘浓度过高,影响矿井安全问题,提出了一种新型风幕集尘除尘系统,经过模拟论证系统可以达到良好的除尘效果。为了使系统的集尘除尘效果更好,应用计算流体力学Fluent软件在系统关键参数同时变化情况下进行数值模拟。模拟结果说明了除尘风筒对系统集尘除尘影响最大,也得到了系统的最佳匹配参数值。     

气流喷射床反应器液体停留时间分布实验与模拟

气流喷射床反应器具有良好的传递性,减少轴向返混,相间接触时间短,气液比(气固比)调节灵活等特点。本文使用脉冲进样法测定了气流喷射床反应器液体的停留时间分布(RTD),并用Fluent软件模拟了实验,初步考察了影响停留时间分布的各因素。结果表明,随着液流量的增大,停留时间逐渐趋于稳定,而气流量对液体停留时间影响较小;Fluent软件得到的模拟值与实验值较吻合,说明模型可用。     

燃气弹射内弹道二维数值仿真软件开发

以燃气式弹射器为研究对象,对燃气弹射器建立二维内弹道数学模型.在.net平台下设计研发了可视化编程软件完成了对零维内弹道数学模型、二维内弹道数学模型数值仿真计算集成,侧重于二维内弹道数学模型仿真,其核心是运用C#语言对Fluent进行二次开发.工程人员在自定义GUI界面进行参数设计,集成软件就可以研究不同配比条件下,压力、速度、温度等流场数据.节省了工程人员大量的时间去掌握研究背景以及Fluent软件的参数设置界面,很大程度上提高了科研人员的工作效率,适合做重复性实验研发,为燃气流场参数的预估和试验测量提供理论和技术支持.     

Mesh-driven vector field clustering and visualization: an image-based approach

Vector field visualization techniques have evolved very rapidly over the last two decades, however, visualizing vector fields on complex boundary surfaces from computational flow dynamics (CFD) still remains a challenging task. In part, this is due to the large, unstructured, adaptive resolution characteristics of the meshes used in the modeling and simulation process. Out of the wide variety of existing flow field visualization techniques, vector field clustering algorithms offer the advantage of capturing a detailed picture of important areas of the domain while presenting a simplified view of areas of less importance. This paper presents a novel, robust, automatic vector field clustering algorithm that produces intuitive and insightful images of vector fields on large, unstructured, adaptive resolution boundary meshes from CFD. Our bottom-up, hierarchical approach is the first to combine the properties of the underlying vector field and mesh into a unified error-driven representation. The motivation behind the approach is the fact that CFD engineers may increase the resolution of model meshes according to importance. The algorithm has several advantages. Clusters are generated automatically, no surface parameterization is required, and large meshes are processed efficiently. The most suggestive and important information contained in the meshes and vector fields is preserved while less important areas are simplified in the visualization. Users can interactively control the level of detail by adjusting a range of clustering distance measure parameters. We describe two data structures to accelerate the clustering process. We also introduce novel visualizations of clusters inspired by statistical methods. We apply our method to a series of synthetic and complex, real-world CFD meshes to demonstrate the clustering algorithm results.     

三维矢量场的流动拓扑结构抽取

提出一种基于关键点分类的三维矢量场流动拓扑结构抽取算法,可应用于三维曲线网格、结构化网格和分块网格中.在许多计算流体力学计算中,存在非滑移边界,这种边界上流体的速度为0.通过分析流场边界的表面摩擦场的拓扑,展示绕壁面流体的流动结构;使用图标定位关键点,可交互式地标记和显示涡核区域,并通过选择暗示螺旋流动的图标,沿着该关键点的实特征值对应的特征矢量方向积分流线来完成.测试结果清晰地展示了关键特征区域的流体流动特征.     

Feature extraction of separation and attachment lines

Separation and attachment lines are topologically significant curves that exist on 2D surfaces in 3D vector fields. Two algorithms are presented, one point-based and one element-based, that extract separation and attachment lines using eigenvalue analysis of a locally linear function. Unlike prior techniques based on piecewise numerical integration, these algorithms use robust analytical tests that can be applied independently to any point in a vector field. The feature extraction is fully automatic and suited to the analysis of large-scale numerical simulations. The strengths and weaknesses of the two algorithms are evaluated using analytic vector fields and also results from computational fluid dynamics (CFD) simulations. We show that both algorithms detect open separation lines-a type of separation that is not captured by conventional vector field topology algorithms     

A new line integral convolution algorithm for visualizingtime-varying flow fields

New challenges on vector field visualization emerge as time dependent numerical simulations become ubiquitous in the field of computational fluid dynamics (CFD). To visualize data generated from these simulations, traditional techniques, such as displaying particle traces, can only reveal flow phenomena in preselected local regions and thus, are unable to track the evolution of global flow features over time. The paper presents an algorithm, called UFLIC (Unsteady Flow LIC), to visualize vector data in unsteady flow fields. Our algorithm extends a texture synthesis technique, called Line Integral Convolution (LIC), by devising a new convolution algorithm that uses a time-accurate value scattering scheme to model the texture advection. In addition, our algorithm maintains the coherence of the flow animation by successively updating the convolution results over time. Furthermore, we propose a parallel UFLIC algorithm that can achieve high load balancing for multiprocessor computers with shared memory architecture. We demonstrate the effectiveness of our new algorithm by presenting image snapshots from several CFD case studies     

Region-of-interest visualization by CAVE VR system with automatic control of level-of-detail

To specify the region of interest (ROI) is an effective approach to visualize large scale simulation data. We have developed a three-dimensional visualization software with ROI function for the CAVE virtual reality systems. This software enables the user to perform fully three-dimensional and interactive visualization of large scale computational fluid dynamics (CFD) data. The user specifies a ROI in the CAVE room by a three-dimensional “mouse-drag”. The data in the specified ROI is automatically extracted from the original CFD data. This ROI procedure can be repeated recursively. The resolution in each ROI is kept approximately constant. A data set of three vector fields and eight scalar fields whose size is about 1 GB each was successfully analyzed.     

Microarchitectural performance comparison of Intel Knights Corner and Intel Sandy Bridge with CFD applications

This paper comparatively evaluates the microarchitectural performance of two representative Computational Fluid Dynamics (CFD) applications on the Intel Many Integrated Core (MIC) product, the Intel Knights Corner (KNC) coprocessor, and the Intel Sand Bridge (SNB) processor. Performance Monitoring Unit-based measurement method is used, along with a two-phase measurement method and some considerations to minimize the errors and instabilities. The results show that the CFD applications are sensitive to architecture factors. Their single thread performance and efficiency on KNC are much lower than that on SNB. Branch prediction and memory access are two primary factors that make the performance difference. The applications’ low-computational intensity and inefficient vector instruction usage are two additional factors. To be more efficient for the CFD applications, the MIC architecture needs to improve its branch prediction mechanism and memory hierarchy. Fine tuning of application codes is also crucial and is hard work.     

FIRST: a flexible and interactive resampling tool for CFD simulation data

We introduce a flexible, variable resolution tool for interactive resampling of computational fluid dynamics (CFD) simulation data on versatile grids. The tool and coupled algorithm afford users precise control of glyph placement during vector field visualization via six interactive degrees of freedom. Other important characteristics of this method include: (1) an algorithm that resamples any unstructured grid onto any structured grid, (2) handles changes to underlying topology and geometry, (3) handles unstructured grids with holes and discontinuities, (4) does not rely on any pre-processing of the data, and (5) processes large numbers of unstructured grid cells efficiently. We believe this tool to be a valuable asset in the engineer's pursuit of understanding and visualizing the underlying flow field in CFD simulation results.     

流线可视化技术研究与进展

流线可视化技术是普遍采用的CFD矢量场可视化工具。简要回顾了流线可视化技术的理论和实际意义，以及流线生成的两类技术；重点针对流场数据和流线表达方法的特点，介绍了流线可视化研究中一些具有共性的问题，以及近年来流线可视化技术的研究热点和动态。     

一个优化运动矢量码率分配的快速算法

从信息论的角度看，运动补偿的最终目的是极小化信源熵率。因此，对具有四叉树结构的运动矢量场，当使用叶部运动矢量替代相应根部运动矢量作运动补偿预测时，若编码运动矢量所增加的熵大于相应补偿帧差所减少的熵，则删除相应的叶部运动矢量，反之，则应使用叶部运动矢量替代根部的运动矢量。依据这一准则，该文通过对正向搜索的运动矢量场进行自下而上反向优化截断，得到了一个全局优化运动矢量场码率分配的快速算法。通过假设补偿帧差系数的选验概率分布，该文首先给出了一个闭式补偿帧差系数熵理论计算公式，考虑到视频压缩的有损特性，然后又对这个闭式理论公式作了带权修正，为了进一步提高运动矢量的编码效率，文中同时也给出了一种运动矢量融合方案。最后，该文在运动补偿的三维小波视频编码系统上对这个算法进行了验证和比较。模拟实验证实该文所提出的运动矢量码率分配算法不仅速度快而且收敛性态稳定，只要提供合适的搜索深度，总可以获得最佳的分配结果。由于优化算法避开了补偿帧差的具体后处理，因此该文的算法也可以应用到传统的DCT视频编码器。     

Sources of error in the graphical analysis of CFD results

Graphical techniques are widely used to analyze CFD solutions. Some of these techniques have inherent errors, making them represent the solution imprecisely. An understanding of these errors is important for proper interpretation of the computed results and for comparison with experiments. Examples include contouring, plotting of vector fields, particle tracing, and computation of flow functions involving integration or differentiation.This paper is declared a work of the U. S. Government and therefore is in the public domain.