CFD软件之phoenics.doc

。1流体模拟软件简介英文名称CFD，主要用于解决工程中的流体和传热问题，目前比较好的CFD软件有：Fluent、CFX、Phoenics、Star-CD，除了Fluent是美国公司软件外，其它三个都是英国公司的产品。 FLUENT FLUENT是目前国际上比较流行的商用CFD软件包，在美国的市场占有率为60%。举凡跟流体，热传递及化学反应等有关的工业均可使用。它具有丰富的物理模型、先进的数值方法以及强大的前后处理功能，在航空航天、汽车设计、石油天然气、涡轮机设计等方面都有着广泛的应用。其在石油天然气工业上的应用包括：燃烧、井下分析、喷射控制、环境分析、油气消散/聚积、多相流、管道流动等等。 Fluent的软件设计基于CFD软件群的思想，从用户需求角度出发，针对各种复杂流动的物理现象，FLUENT软件采用不同的离散格式和数值方法，以期在特定的领域内使计算速度、稳定性和精度等方面达到最佳组合，从而高效率地解决各个领域的复杂流动计算问题。基于上述思想，Fluent开发了适用于各个领域的流动模拟软件，这些软件能够模拟流体流动、传热传质、化学反应和其它复杂的物理现象，软件之间采用了统一的网格生成技术及共同的图形界面，而各软件之间的区别仅在于应用的工业背景不同，因此大大方便了用户。其各软件模块包括： GAMBIT专用的CFD前置处理器，FLUENT系列产品皆采用FLUENT公司自行研发的Gambit前处理软件来建立几何形状及生成网格，是一具有超强组合建构模型能力之前处理器，然后由Fluent进行求解。也可以用ICEM CFD进行前处理，由TecPlot进行后处理。 Fluent5.4基于非结构化网格的通用CFD求解器，针对非结构性网格模型设计，是用有限元法求解不可压缩流及中度可压缩流流场问题的CFD软件。可应用的范围有紊流、热传、化学反应、混合、旋转流（rotating flow）及震波（shocks）等。在涡轮机及推进系统分析都有相当优秀的结果，并且对模型的快速建立及shocks处的格点调适都有相当好的效果。 Fidap基于有限元方法的通用CFD求解器，为一专门解决科学及工程上有关流体力学传质及传热等问题的分析软件，是全球第一套使用有限元法于CFD领域的软件，其应用的范围有一般流体的流场、自由表面的问题、紊流、非牛顿流流场、热传、化学反应等等。 FIDAP本身含有完整的前后处理系统及流场数值分析系统。 对问题整个研究的程序，数据输入与输出的协调及应用均极有效率。 Polyflow针对粘弹性流动的专用CFD求解器，用有限元法仿真聚合物加工的CFD软件，主要应用于塑料射出成形机，挤型机和吹瓶机的模具设计。 Mixsim针对搅拌混合问题的专用CFD软件，是一个专业化的前处理器，可建立搅拌槽及混合槽的几何模型，不需要一般计算流力软件的冗长学习过程。它的图形人机接口和组件数据库，让工程师直接设定或挑选搅拌槽大小、底部形状、折流板之配置，叶轮的型式等等。MixSim随即自动产生3维网络，并启动FLUENT做后续的模拟分析。 Icepak专用的热控分析CFD软件，专门仿真电子电机系统内部气流，温度分布的CFD分析软件，特别是针对系统的散热问题作仿真分析，藉由模块化的设计快速建立模型。 CFX CFX是由英国AEA公司开发，是一种实用流体工程分析工具，用于模拟流体流动、传热、多相流、化学反应、燃烧问题。其优势在于处理流动物理现象简单而几何形状复杂的问题。适用于直角/柱面/旋转坐标系，稳态/非稳态流动，瞬态/滑移网格，不可压缩/弱可压缩/可压缩流体，浮力流，多相流，非牛顿流体，化学反应，燃烧，NOx生成，辐射，多孔介质及混合传热过程。CFX采用有限元法，自动时间步长控制，SIMPLE算法，代数多网格、ICCG、Line、Stone和Block Stone解法。能有效、精确地表达复杂几何形状，任意连接模块即可构造所需的几何图形。在每一个模块内，网格的生成可以确保迅速、可靠地进行，这种多块式网格允许扩展和变形，例如计算气缸中活塞的运动和自由表面的运动。 滑动网格功能允许网格的各部分可以相对滑动或旋转，这种功能可以用于计算牙轮钻头与井壁间流体的相互作用。CFX引进了各种公认的湍流模型。例如：k-e模型，低雷诺数k-e模型，RNG k-e模型，代数雷诺应力模型，微分雷诺应力模型，微分雷诺通量模型等。CFX的多相流模型可用于分析工业生产中出现的各种流动。包括单体颗粒运动模型，连续相及分散相的多相流模型和自由表面的流动模型。 CFX-TASCflow在旋转机械CFD计算方面具有很强的功能。它可用于不可压缩流体，亚/临/超音速流体的流动，采用具有壁面函数的k-e模型、2层模型和Kato-Launder模型等湍流模型，传热包括对流传热、固体导热、表面对表面辐射，Gibbs辐射模型，多孔介质传热等。化学反应模型包括旋涡破碎模型、具有动力学控制复杂正/逆反应模型、Flamelet模型、NOx和碳黑生成模型、拉格朗日跟踪模型、反应颗粒模型和多组分流体模型。CFX-TurboGrid是一个用于快速生成旋转机械CFD网格的交互式生成工具，很容易用来生成有效的和高质量的网格。 PHOENICS Phoenics是英国CHAM公司开发的模拟传热、流动、反应、燃烧过程的通用CFD软件，有30多年的历史。网格系统包括：直角、圆柱、曲面（包括非正交和运动网格，但在其VR环境不可以）、多重网格、精密网格。可以对三维稳态或非稳态的可压缩流或不可压缩流进行模拟，包括非牛顿流、多孔介质中的流动，并且可以考虑粘度、密度、温度变化的影响。在流体模型上面，Phoenics内置了22种适合于各种Re数场合的湍流模型，包括雷诺应力模型、多流体湍流模型和通量模型及k-e模型的各种变异，共计21个湍流模型，8个多相流模型，10多个差分格式。 Phoenics的VR（虚拟现实）彩色图形界面菜单系统是这几个CFD软件里前处理最方便的一个，可以直接读入Pro/E建立的模型（需转换成STL格式），是复杂几何体的生成更为方便，在边界条件的定义方面也极为简单，并且网格自动生成，但其缺点则是网格比较单一粗糙，针对复杂曲面或曲率小的地方的网格不能细分，也即是说不能在VR环境里采用贴体网格。另外VR的后处理也不是很好。要进行更高级的分析则要采用命令格式进行，但这在易用性上比其它软件就要差了。 另外，Phoenics自带了1000多个例题与验证题，附有完整的可读可改的输入文件。其中就有CHAM公司做的一个PDC钻头的流场分析。Phoenics的开放性很好，提供对软件现有模型进行修改、增加新模型的功能和接口，可以用FORTRAN语言进行二次开发。 另一个CFD软件STAR-CD的创始人与Phoenics的创始人Spalding都是英国伦敦大学同一教研室的教授，他们的软件的核心算法大同小异，这里对STAR-CD就不做详述。2.PHOENICS入门本文目的是帮助那些PHOENICS的初学者在不需要深入了解该软件的情况下可以进行一些简单的流动计算。PHOENICS界面包括模型编辑界面，数值计算运行界面和计算结果查看界面三部分。利用模型编辑界面来建立几何模型是最适合初学者的，因为它不仅简单易懂，而且还可以自动生成PHOENICS输入语言所编写的Q1文件而不用使用者学习PHOENICS输入语言。当使用者对PHOENICS有了一定的了解以后，可以利用PHOENICS输入语言直接编写Q1文件或利用FORTRAN语言更深入地编写一些模块。计算结果查看界面可以将计算结果以形象易懂地方式表现出来，也可以利用PHOENICS中的图形处理模块将计算结果按我们想要的形式画出来，另外为了更好地观察计算结果和提取有用信息可将计算结果进行格式转换再用各种常用的图象处理软件处理，如TECPLOT，ORINGE，MATLAB等。3.模型编辑界面的控制面板图 一.4.模型编辑界面的控制面板图 二5.计算结果查看界面的控制面板图6.模型编辑界面和计算结果查看界面的通用界面图7.PHOENICS入门简介（英文版）-1正在读取此图片的详细信息，请稍候 . INTRODUCTION TO PHOENICS ContentsWhat PHOENICS does The Structure of PHOENICS How the problem is defined How PHOENICS makes the predictions How the results are displayed Hardware Customization of PHOENICS Learning to use PHOENICS The Virtual-Reality Interface EARTH GROUND Built-in Features of EARTH Display via VR PHOTON AUTOPLOT Other Input and Output Facilities Programmability PLANT What PHOENICS doesPHOENICS, operated by its users, performs three main functions: 1.problem definition, in which the user prescribes the situation to be simulated and the questions to which he wants the answers; 2.simulation, by means of computation, of what the laws of science indicate will PROBABLY take place in the prescribed circumstances; 3.presentation of the results of the computation, by way of graphical displays, tables of numbers, and other means. PHOENICS, like many but not all CFD codes, has a distinct software module for each function. This sub-division allows functions (1) and (3), say, to be performed on the users home computer, while the power-hungry function (2) can be carried out remotely.The Structure of PHOENICS PHOENICS has a planetary arrangement, with a central core of subroutines called EARTH, and a SATELLITE program, which accepts inputs through the Virtual Reality (VR) interface or otherwise, which correspond to a particular flow simulation. EARTH and SATELLITE are distinct programs. SATELLITE is a data-preparation program; it writes a data file which EARTH reads. PHOENICS users work mainly with SATELLITE, but they can access EARTH also in controlled ways. GROUND is the EARTH subroutine which users access when incorporating special features of their own. The diagram below is a schematic of the three main functions of PHOENICS, i.e., 1.Pre-processor - problem definition 2.Solver - simulation 3.Post-processor - presentation of results8.PHOENICS入门简介（英文版）-2How the problem is definedProblem definition normally involves making statements about: geometry, ie shapes, sizes and positions of objects and intervening spaces; materials, ie thermodynamic, transport and other properties of the fluids and solids involved; processes, for example:- whether the materials are inert or reactive; whether turbulence is to be simulated and if so by what model; whether temperatures are to be computed in both fluids and solids; and whether stresses in solids are to be computed; grid, ie the manner and fineness of the sub-division of space and time, ie what is called the discretization; and other numerical (ie non-physical) parameters affecting the speed, accuracy and economy of the simulation. SPECIAL FEATURES of problem definition which distinguish PHOENICS are:- problem definition can be carried out in a VARIETY of ways, selected by the user according to his experience or preference; thus, engineers who use CAD packages can export the corresponding files directly to PHOENICS-VR (ie Virtual Reality); VR, and other interactive input procedures of PHOENICS, create as a record a command file, called Q1, which experienced users of PHOENICS can modify by editing, thus sparing themselves the tedium (as they sometimes see it) of further interactive sessions; the PLANT feature of PHOENICS allows the property laws of new materials to be supplied by the writing of formulae into the command file; and hundreds of quality-assured command files are supplied with the standard PHOENICS sofware in a set of easily accessible LIBRARIES, so that the user rarely has to start from scratch. PHOENICS has indeed its own high-level input language, called PIL, in which the Q1 files are written.PIL is a directly-interpreted language, requiring no compilation; and its capabilities include:- direct assignment, as in:NX=10; CARTES=F (ie false); PI=3.1416- interrogation, as in:NX?; CARTES? which print their values- arithmetic commands, as in: NX=2*NY- conditional settings, as in: IF(NX.EQ.10) THEN; CARTES=F; ENDIF- DO loops, as in: DO II=1,3MESG(Three cheers! HURRAH! ENDDO- INCLUDE commands, as in: INCL(file name- LOAD commands, as in:L(library case number- numerous other facilities for setting grids, boundary and initial conditions, material properties, output needs and other data.So far as is known, PIL is the most powerful and flexible input language ever devised for the setting up of CFD problems.How PHOENICS makes the predictionsPHOENICS simulates the prescribed physical phenomena by:- expressing the relevant laws of physics and chemistry, and the models which supplement them, in the form of equations linking the values of pressure, temperature, concentration, etc which prevail at clusters of points distributed through space and time; locating these point-clusters (which constitute the computational grid) sufficiently close to each other to represent adequately the continuity of actual objects and fluids; solving the equations by systematic, iterative, error-reduction methods, the progress of which is made visible on the VDU screen; enabling the computations to be interrupted, and the controlling settings to be modified, as the user desires; terminating when the errors have been sufficently reduced. SPECIAL FEATURES relating to how PHOENICS makes the predictions are: PHOENICS can handle a WIDER RANGE OF PHYSICAL PROCESSES, and is equipped with a MORE EXTENSIVE VARIETY OF PHYSICAL MODELS, than any of its competitors. The ways in which these physical processes are represented in the computer language, Fortran, are visible and accessible to users, and NOT hidden as in most other codes. The relevant coding, called GROUND, constitutes more than fifty percent of the EARTH module. This open-source coding is written in a well-annotated easy-to-follow manner, in order that users can, if they wish: ounderstand, odecide whether CHAMs provision meets their needs, and oeither modify it or add coding of their own. For users who are not confident of their ability to do this, CHAM has provided the PLANT option, which reduces the users duties to entering the required formulae into the command file. Unlike those other CFD codes which cope with geometrical complexity by the use of unstructured grids, PHOENICS retains the computational economy of the more-orderly STRUCTURED GRIDS, while utilising MULTI-BLOCK, FINE-GRID-EMBEDDING and PARSOL, ie cut-cell techniques for handling geometric complexity. A related and unique feature is the MOVSOL, feature, which makes it easy, economical and accurate to allow curvilinear solids to move relative to each other across curvilinear grids. PHOENICS possesses a unique EXPERT feature, which automatically optimises the numerical parameters as the computation proceeds. PHOENICS also employs an economical and unique-to-it PARABOLIC grid when flow is of the very common boundary-layer character. The PHOENICS grid has lent itself particularly well to DOMAIN-DECOMPOSITION, which is what is needed for parallel computers. How the results are displayedPHOENICS can display the results of its flow simulations in a wide variety of forms.It has its own stand-alone graphics package called PHOTON; and it can also export results to such third-party packages as TECPLOT, AVS, and FEMVIEW.Unique to PHOENICS is its ability to take the results of its flow predictions back into the same VIRTUAL-REALITY environment as is used for setting up the problem at the start.This facilitates understanding by the user; and it also affords a means of conveying the significance of the flow-simulation operation to interested but non-technical persons, eg. high-level managers.Of course, numerical results are also provided, in the RESULT file.This, when the appropriate commands in the Q1 file, can provide either sparse or voluminous information.9.PHOENICS入门简介（英文版）-3The Virtual-Reality InterfaceData input via the VR-EditorThe Virtual-Reality user interface assists users to set up flow-simulation calculations, without having to learn the PHOENICS Input Language. In this data-input mode, it is called the VR-Editor.The appearance of VR-Editor the screen is shown on the next panel.It suffices therefore to say here that objects of all kinds (blockages, inlets, outlets, sources, etc) can be brought in by appropriate mouse-clicks, and then given such locations, shapes, sizes, materials and other attributes as are needed to start the flow-simulating calculation10.PHOENICS入门简介（英文版）-4This is the top part of the menu which appears when the Main Menu button is pressed. It enables whole-domain settings to be made.What the Virtual-Reality Editor createsThe VR-Editor records the settings made by the user during his editing session in an ASCII file known as Q1.This file can be read, understood (if the user knows something of PIL, the PHOENICS Input Language) and edited. Usually, however, it will simply be stored for later use.In any case, the flow-simulation can begin immediately, if the user wishes, because two other files will also have been automatically written, one of which (FACETDAT) conveys the necessary geometrical information, while the other (EARDAT) carries everything else that the solver module needs to know.The switching from the VR-Editor to the solver, and for that matter to any other PHOENICS module, is rendered particularly easy by the pull-down menus accessible from the top bar of the VR-Editor screen11.PHOENICS入门简介（英文版）-5EARTH The solver EARTH starts with a MAIN program, open to users for re-dimensioning operations.The other user-accessible source subroutines are GROUND, GREXn (i.e., GROUND example, number n) and others of the same kind.EARTH contains sequences for: storage allocation formulation of finite-volume equations iterative solution of finite-volume equations calling GROUND when required termination of iteration sequences output of results A Typical EARTH Convergence Monitor PlotGROUND GROUND is a subroutine which is called by EARTH at pre-set points of the solution cycle. If the user inserts appropriate FORTRAN statements at the entry points in GROUND, EARTH absorbs these into the solution process.Special communication subroutines allow the user to extract information from EARTH, manipulate it in GROUND and then return new information or instructions to EARTH.Many service sub-routines are attached, performing commonly-needed arithmetic operations. These greatly reduce the users need to write FORTRAN-coding sequences.Built-In Features Of EARTHConservation principles PHOENICS sets up and solves finite-domain equivalents of the basic differential equations.It thus embodies the laws of conservation of mass, momentum and energy, for either one or two phases. More-than-2-phase flows can also be represented in a number of ways.Any property obeying a balance equation can be represented, including species concentration, turbulence energy, vorticity and its fluctuations radiation fluxes, electric potential, etc. Solution procedures PHOENICS contains solvers for sets of linear simultaneous equations. Options include: point-by-point, slab-wise, and whole-3D-field. The coupled hydrodynamic equations are solved by the so-called SIMPLEST procedure. For two-phase flows, the IPSA version of this is used. Details of these procedures are given in the published CFD literature.Handling special requirements EARTH can handle problems which are: steady or unsteady, parabolic or elliptic, an