Gambit Modeling Guide(4)

4. 设定区域类型4.1 概述区域类型设定确定了该区域截面和指定区域内的模型的实体和操作特征。

有两种典型的区域类型设定：•边界类型•连续介质类型边界类型设定，例如WALL或者VENT，确定了模型的外部或者内部边界的特点。

连续介质类型，例如FLUID或者SOLID，确定了模型内部指定区域的特点。

以下部分强简要介绍边界类型和连续介质类型设定并结合包含简单几何结构的计算模型示例阐述它们定义的目的。

4.1.1 边界类型设定边界类型设定确定了模型中那些代表模型边界的拓扑结构实体的物理特性和操作特性。

例如，如果用户将三维模型的一个面实体指定为INFLOW边界类型，该模型则被设定为介质从该设定面流入模型区域。

类似的，如果用户对于一个二维模型的边实体指定为SYMMETRY边界类型，则该模型被设定为流量、温度和压力梯度沿着指定边等于零。

因此，紧邻该边两侧的区域内的物理条件相同。

注意：要对于一个FLUENT解算器应用周期性边界条件，用户必须首先在应用边界条件的一组边（二维）或者一组面（三维）之间建立网格坚固连接。

（关于网格坚固连接的详细说明，参阅3.2.3部分。

）另外，用户必须为该组中的两条边或者两个面都设定PERIODIC 边界类型，并且这两条边（或者两个面）都必须作为一个单独实体的组成部分。

（如图4－1。

）图4－1：周期性边界条件设定——FLUENT解算器关于设定边界类型要求的步骤的完整说明，请参阅下面的4.2.1部分。

4.1.2 连续介质类型设定连续介质类型设定确定模型你不指定区域的物理特性。

例如，如果用户对于一个体积实体指定了FLUID连续介质类型设定，该模型设定使得动量方程、连续性和网格节点和单元之间的物性传递存在于该体积中。

相反的，如果用户对于一个体积实体指定了SOLID连续介质类型，则仅仅有能量和物性传递方程（没有对流）将用用于该体积中现有的网格节点或者单元。

4.1.3 区域类型设定的影响作为区域类型设定对于计算模型设定的影响的一个示例，考虑如图4－2所开始的几何结构——它包含一个直椭圆柱体。

1.基本几何结构的创建和网格化本章介绍了GAMBIT中一个简单几何体的创建和网格的生成。

在本章中将学习到：z启动GAMBITz使用Operation工具箱z创建一个方体和一个椭圆柱体z整合两个几何体z模型显示的操作z网格化几何体z检查网格的品质z保存任务和退出GAMBIT1.1 前提在学习本章之前，认为用户还没有GAMBIT的使用经验，不过，已经学习过前一章“本指南的使用”，并且熟悉GAMBIT界面以及本指南中所使用的规约。

1.2 问题描述本模型由两个相交的方体和椭圆柱体构成，其基本图形形状如图1-1所示。

图1-1：问题说明1.3策略本章介绍使用GAMBIT生成网格的基本操作，特别地，将介绍：z如何使用“top-down”固体建模方法来方便地创建几何体z如何自动生成六面体网格“top-down”方法的意思是用户可以通过生成几何体（如方体、柱体等）来创建几何结构，然后，对它们进行布尔操作（如整合、剪除等），以这种方式，用户不用首先去创建作为基础的点、边和面，就可以快速创建出复杂的几何形体。

一旦创建出一个有效的几何模型，网格就可以直接并且自动地（很多情况下）生成。

在本例子中，将采用Cooper网格化算法来自动生成非结构化的六面体网格。

更复杂的几何结构在生成网格之前可能还需要进行手工分解，这将在后面进行介绍。

本章的学习步骤如下：z创建两个几何体（一个方体和一个椭圆柱体）z整合两个几何体z自动生成网格z检查网格的品质为了使本章的介绍尽量简短，一些必要的步骤被省略了：z调节几何体单边上节点的分布z设置连续介质类型（例如，标识哪些网格区是流体，哪些网格区是固体）和边界类型这些方面的详细内容，也包括其他方面，在随后的章节将涉及到。

1.4步骤输入gambit -id basgeom启动GAMBIT。

这就打开了GAMBIT的图形用户界面(GUI)（图1-2）。

GAMBIT把设定的名称（本例子中为basgeom）作为她将创建的所有文件的词头，如：basgeom.jou。

Tutorial:Introduction to Size FunctionsPurposeThe purpose of this tutorial is to introduce you to the use of size functions to control the size of mesh intervals for edges and mesh elements for faces and volumes.Based on their application,there are four types of size functions:fixed,curvature,proximity and meshed.This tutorial shows you how to use these size function types to refine a mesh in regions surrounding a specified entity and how to combine boundary layers and size functions for better mesh quality.PrerequisitesThis tutorial assumes that you are familiar with the GAMBIT interface and have a basic understanding of geometry creation and size functions.If you have not used size functions before,you can refer to Section5.2:Size Functions,in the GAMBIT Modeling Guide(http://www.fl/gambit2/doc/doc f.htm).Problem DescriptionYou will create a rectangular face,an elliptical cylindrical volume and a brick geometry and mesh them using the Fixed,Curvature,and Proximity size functions,respectively.Using a journalfile,you will then create and partially premesh2-D and3-D geometry.You will then use the meshed size function to grow the full mesh from the premeshed sections of the geometry.To create a size function,you need to define the Source and Attachment entities and param-eters such as,Growth rate,Size limit,Start size,Angle,and Cells/gap.The Growth rate and Size limit parameters are common to the four size functions.The additional parameter specific to three size functions,which is the initialization parameter used to create mesh on the source entities,is listed below:Type of Size Function Parameter Specific to the FunctionFixed Start sizeCurvature AngleProximity Cells/gapThe meshed size function does not require an initialization parameter,since we are starting from an existing mesh at the source entities.Introduction to Size FunctionsYou can specify more than one size function on any face or volume.Size functions can be used with hexahedral,tetrahedral or hybrid volume meshes and quadilateral or triangular face meshes.Since,you can control the number of elements in mapped or submapped meshes using edge grading,size functions are used in more complex geometries where tetrahedral or Cooper meshing schemes are required.Fixed Size FunctionThe Fixed size function is used to control the maximum mesh-element edge lengths in a model.Step1:Geometry1.Start GAMBIT with the identifier pipe.2.Create a rectangle with the following dimensions:Width Height10103.Create a circle with a value of Radius as1.4.Subtract the circle from the square.(a)In the Subtract Real Faces form,select face.1and face.2for Face and Subtract Facesrespectively.(b)Retain the default values of the other parameters and click Apply.5.Make two copies of the face and translate it.(a)In the Move/Copy Faces form,select face.1for Faces.(b)Select Copy and set the number of copies to2.(c)Under Global,set the value of x:to12.(d)Retain the default values of the other parameters and click Apply.Step2:Mesh the First Face1.Mesh the inner circular loop on thefirst face.(a)In the Mesh Edges form,for Edges,select the edge corresponding to the innercircular loop.(b)Set the Interval size to0.2and click Apply.2.Mesh thefirst face(see Figure1).(a)In the Mesh Faces form,select face.1for Faces and Tri for Elements:.(b)Retain the default values for the other parameters and click Apply.Introduction to Size FunctionsFigure1:Mesh on face.1Step3:Mesh the Second Face Using the Fixed Size Function1.Define afixed type function(fix1)on the second face(face.2).(a)On the Entities:Source:option button,select Edges and select the edge corre-sponding to the inner circular loop.(b)On the Entities:Attachment:option button,select the second face(face.2).(c)Set the values for the remaining parameters as follows:Start size Growth rate Size limit Label0.2 1.50.5fix12.Initialize the size function.(a)In the View Size Function form,selectfix1for S.Function and click Initialize.Note:The Iso-value:ranges from0.2to0.5.You can move the slider bar to examine the extent of the size function.The size function will not encompass the entireface.In the region excluded by the isovalues from0.2to0.5,the elements willhave a constant size of0.5.3.Mesh the second face.(a)Select face.2for Faces and Tri for Elements:.(b)Click Apply.The mesh obtained is muchfiner than the mesh on thefirst face because the valueof Size limit was specified as0.5.Introduction to Size Functions4.Delete the mesh on the second face.You will now adjust the size function parameters to get a coarser mesh on the secondface.5.Modify the size function(fix1)on the second face.(a)Change the value of Size limit to1and retain the default values of the otherparameters.6.Reinitialize the size function.Note:The Iso-value:now ranges from0.2to1.You can move the slider bar to examine the extent of the size function.The size function will not encompass theentire face.In the region excluded by the isovalues from0.2to1,the elementswill have a constant size of1.7.Remesh the second face(see Figure2).With the modified size function,you get a coarser mesh on the second face.Figure2:Mesh on face.2Step4:Mesh the Third Face Using the Fixed Size Function1.Define afixed type function(fix2)on the third face.(a)Set the Source:to the edge corresponding to the inner circular loop.(b)Set the Attachment:to face.3.(c)Set the values for the remaining parameters as follows:Start size Growth rate Size limit Label0.2 1.21fix2Introduction to Size Functions2.Initialize the size function.(a)In the View Size Function form,selectfix2for S.Function and click Initialize.Note:The Iso-value:ranges from0.2to1.You can move the slider bar to examine the extent of the size function.The size function will encompass the entire face.In the region excluded by the isovalues from0.2to1,the elements will have aconstant size of1.3.Mesh the third face with Tri elements.Figure3:Mesh on face.3You can compare the meshes shown in Figures1,2,and3.All the three meshes have the same mesh sizes on the edges,but the meshes created using a size function have a prescribed growth rate that results in fewer elements.Introduction to Size FunctionsCurvature Size FunctionThe Curvature size function controls the angles between the normals for adjacent mesh ele-ments and is useful when the model contains highly curved surfaces.Step1:Geometry1.Delete the previously created faces(face.1,face.2,and face.3).2.Create an elliptical cylinder with the following parameters:Height Radius1Radius2Axis Location1025Centered Z3.Make two copies of the elliptical cylinder and translate them.(a)In the Move/Copy Volumes form,select volume.1for Volumes and set the numberof copies to2.(b)Under Global,set the value of y:to12and x:and z:to0.(c)Retain the default values of the other parameters and click Apply.Step2:Mesh the First Volume1.In the Mesh Volumes form,select volume.1for Volumes and Tet/Hybrid for Elements:.2.Set the Interval size to2and click Apply.Figure4:Mesh on volume.1The mesh poorly represents the model in the regions where the edges are highly curvedand the surfaces are non planar.Introduction to Size Functions Step3:Mesh the Second Volume Using the Curvature Size Function1.Define a curvature type function(curv1).(a)Select Curvature for Type:.(b)On the Entities:Source:option button,select Faces and select the lateral face ofvolume.2.(c)On the Entities:Attachment:option button,select Volumes and select the volumeas volume.2.(d)Set the values for the remaining parameters as follows:Angle Growth rate Size limit Label40 1.22curv12.Mesh the second volume(volume.2)using tetrahedral elements.Figure5:Mesh on volume.2Now,the mesh is a much better approximation of the model where the regions are highly curved.Introduction to Size FunctionsStep4:Mesh the Third Volume Using the Curvature Size Function1.Define a curvature type function(curv2)on the third volume(volume.3).(a)Set the Source:to the lateral face of volume.3and the Attachment:to volume.3.(b)Change the value of Angle to20,and refer to the definition of curv1for values ofthe other parameters.2.Mesh the third volume(volume.3)using tetrahedral elements.Figure6:Mesh on volume.3pare the meshes for the second and third volume(see Figure7).The value of the angle determines the maximum angle between the normal vectors to adjacent mesh elements.Thus,a smaller angle(20degrees)will produce a better approximation toa curved edge than a larger angle(40degrees).Introduction to Size FunctionsFigure7:Magnified View of the Curved Edges of volume.3and volume.2Introduction to Size FunctionsProximity Size FunctionThe Proximity size function controls the number of mesh elements in faces between two geometric entities and is useful when there are small gaps in the model.Step1:Geometry1.Delete the previously created volumes(volume.1,volume.2and volume.3).2.Create a brick with the following dimensions:Width Depth Height Direction555Centered3.Create a thinner brick with the following dimensions:Width Depth Height Direction0.255Centered4.Move the thinner brick.(a)In the Move/Copy Volumes form,select volume.2or Volumes,and under Global,setthe values of x:to2,y:to0,and z:to2.5.5.Subtract the thinner brick from the larger brick.(a)In the Subtract Real Volumes form,select volume.1for Volume and volume.2forSubtract Volumes and click Apply.Figure8:Subtracted Volume(volume.1)There is a thin rectangular face(face.11)and a small gap of0.4width within thevolume bounded by the faces,face.13and face.1.6.Make a copy of the volume and translate it.(a)In the Move/Copy Volumes form,select volume.1for Volumes and set the numberof copies to1.(b)Under Global,set the value of x:to6,and y:and z:to0.(c)Retain the default values of the other parameters and click Apply.Step2:Mesh the First Volume Using Proximity Size Function1.Define a proximity type function(prox1)on thefirst volume(volume.1).(a)Select Proximity for Type:.(b)On the Entities:Source:option button,select Faces and select the thin rectangularface(face.11)of volume.1.(c)On the Entities:Attachment:option button,select Volumes and select the volumeas volume.1.(d)Set the values for the remaining parameters as follows:Cells/gap Growth rate Size limit Label3 1.31prox12.Mesh volume.1using tetrahedral elements.Figure9:Mesh on volume.1Figure10:Magnified View of Mesh on volume.1There are3elements in the thin rectangular face(face.11),however there is only one element in the thin gap bounded by the faces,face.13and face.1.Step3:Mesh the Second Volume Using Proximity Size Function1.Define a proximity function(prox2)on the second volume.(a)Set the Source:to the three faces(face.17,face.16,and face.25)of volume.2.(b)Set the Attachment:to volume.2,and refer to the definition of prox1for values ofthe other parameters.2.Mesh volume.2using tetrahedral elements.Now,there are3elements in the thin rectangular face(face.17)and three elements in the thin gap bounded by the faces,face.16,and face.25(see Figure12).Figure11:Mesh on volume.2Figure12:Magnified View of Mesh on volume.2Meshed Size FunctionThe meshed size function is used to grow mesh from source entities,which have been premeshed.This size function can be used for growing a graded surface mesh from pre-meshed edges or graded volume meshes from premeshed faces.You will need the journal file,meshed-sf-prep.jou for this section.Step1:Geometry and Premeshing using a Journal File1.Start GAMBIT with the identifier meshed-sf.2.In the File menu,select Run Journal....3.In the Run Journal form,select the Edit/Run mode.4.Click Browse...and navigate to the directory containing the journalfile meshed-sf-prep.jou.5.Select thefile meshed-sf-prep.jou and click Accept.6.In the Edit/Run Journal form,right-click the mouse and choose Select All in the drop-down menu.7.Click Step repeatedly to execute the commands in the journalfile one after another. Note:Observe the sequence of events on the screen from geometry creation to meshing ofedges and face.You may need to click the button to view all geometry.Step2:Mesh the First Face Using a Meshed Size Function1.Create a meshed size function with source as the edges and attachment entity asface.1.(a)Select Meshed as Type:.(b)On the Entities:Source:option button,select Edges and select all four premeshededges of thefirst face.(c)On the Entities:Attachment:option button,select thefirst face(face.1).(d)Set the values of the parameters as follows:Growth Rate Size Limit Label1.12meshed12.Mesh the face with quadrilaterals using the quad pave scheme.Figure13:Face Meshed Using Quad Pave SchemeIt can be observed that the mesh grows into the face from the edge meshes(Figure13).The face mesh can be made smoother orfiner by adjusting the growth rate and the size limit.This is useful for meshing complex faces containing edge meshes with different grading and spacing.Step3:Mesh the Volume Using a Meshed Size Function3.Create a meshed size function with source as the meshed face and attachment entityas volume.(a)Select Meshed as Type:.(b)On the Entities:Source:option button,select the Faces and select the premeshedface of the volume.(c)On the Entities:Attachment:option button,select Volume and select the volume(volume.1).(d)Set the values of the parameters as follows:Growth Rate Size Limit Label1.24meshed24.Mesh the volume with a Tet/Hybrid mesh using the Tgrid meshing scheme.Figure14:Cross-Sectional View of Mesh Along Length of the Volume It can be observed that the mesh grows from the premeshed face into the volume(Fig-ure14).The mesh can be changed by changing the growth rate and the size limit.This is useful in ensuring a smooth transition in mesh between different sections of a larger geometry or in growing a volume mesh from premeshed complex surfaces.In addition, the meshed sizing function can be used for creating a volume mesh grown from the end-capping surface of a prismatic boundary layer grown from surface meshes.Combining the Size Function and Boundary LayerSizing functions can also be combined with boundary layers.In the following example,the volume contains an interior void and the boundary layer must be attached to all the interior faces of this void.In this case,the internal continuity must be turned on.Step1:Geometry1.Delete the previously created volumes(volume.1and volume.2).2.Create a brick with the following dimensions:Width Depth Height Direction141414Centered3.Create an elliptical cylinder with the following parameters:Height Radius1Radius2Axis Location513Centered Z4.Subtract the cylinder from the brick.5.Make two copies of the subtracted volume and translate it.(a)Under Global,set the value of x:to16and y:and z:to0.Step2:Mesh the First Volume Using Size Functions1.Define a curvature type function curvbl1on thefirst volume(volume.1).(a)Select Curvature for Type:.(b)On the Entities:Source:option button,select Faces and select the lateral face ofthe cylinder.(c)On the Entities:Attachment:option button,select Volumes and select the volumeas volume.1.(d)Set the values for the remaining parameters as follows:Angle Growth rate Size limit Label30 1.31curvbl12.Mesh the volume using tetrahedral elements.3.Examine the mesh(see Figure15).(a)Set the Display Type:to Plane and select the tetrahedral3D Element.Figure15:Slice of the Mesh in the z directionStep3:Mesh the Second Volume Using Size Functions and Boundary Layer1.Define a curvature type function(curvbl2)on the second volume using the definitionfor curvbl1.2.Create a boundary layer for volume.2using the Uniform algorithm.(a)Set the values of the following parameters:First row Growth factor Rows0.2 1.23(b)Turn on Internal continuity.(c)Define the three faces(face.16,face.17,and face.18)of the cylinder as the At-tachment:.(d)Retain the default values for the other parameters and click Apply.3.Mesh the volume using tetrahedral elements.4.Examine the mesh.(a)Set the Display Type:to Plane and select the wedge3D Element.(b)Slide the slider bar in the Z direction(see Figure16).As you have used the uniform based boundary layer,you will see that the heightof thefirst layer of prism elements is constant.Figure16:Magnified View of the Prism Elements in the Boundary Layer(c)Select the tetrahedral3D Element and examine the growth of the elements out-wards from the interior void(see Figure17).Figure17:Slice of the mesh in the z directionStep4:Mesh the Third Volume Using Size Functions and Boundary Layer1.Define a curvature type function(curvbl3)on the third volume using the definition forcurvbl1.2.Create a boundary layer for volume.3using the Aspect ratio based algorithm.(a)Set the values of the following parameters:First percent Growth factor Rows30 1.23(b)Turn on Internal continuity.(c)Define the three faces(face.25,face.26,and face.27)of the cylinder as the At-tachment:.3.Mesh the volume using tetrahedral elements.4.Examine the mesh.(a)Set the Display Type:to Plane and select the wedge3D Element.(b)Slide the slider bar in the Z direction(see Figure18).Figure18:Magnified View of the Prism Elements in the Boundary LayerAs you have used the aspect ratio based boundary layer,you will see that theheight of thefirst layer of prism elements is not constant.Introduction to Size Functions(c)Select the tetrahedral3D Element and examine the growth of the elements out-wards from the interior void(see Figure19).Figure19:Slice of the Mesh in the z directionc Fluent Inc.June3,200521。

4. 燃烧室模型的建立（3－D ）在这份指导书中，你可以通过运GAMBIT 中的top-down 几何结构法来为燃烧室生成几何模型（用实体来生成容积）。

你可以通过非结构化六面体网格法来为画出的燃烧室几何体划分网格。

在这份指导书中你可以学习到如何去：● 移动一个体积；● 从一个体积中扣除另一个；● 把一个体积阴影化；● 交叉两个体积；● 混合一个体积的边；● 通过对面进行扫描来生成体积；● 为读入FLUENT/UNS来准备网格。

4.1 前提这份指导书假定读者已经掌握了指导书1并且已对GAMBIT 界面相当熟悉。

4.2 问题描述这个问题在图4－1中以图解的形式表示出来。

此几何体包括一个简化的向燃烧腔加料的燃料喷嘴，在这个指导书中由于几何结构对称你可以仅作出燃烧室几何体的1/4模型。

喷嘴包括两个同心管，其直径分别是4个单位和10个单位，燃烧室的边缘与喷嘴下的壁面融合在一起。

4.3 策略在这份指导书中，你可以运用top-down 几何结构法来生成燃烧室几何体，你可以生成体积（在本例中为方体和圆体）并用布尔运算把它们结合起来，交叉、扣除这些体积以生成基本体积，最后，通过“融和”命令，你可以舍掉一些边界以完成几何体生成。

在这个模型例子中，简单的选择捡起几何体并用六面体单元对整个区域进行网格划分是不可能的，由于Cooper 工具（在本向导中要应用）需要两组面，一组平行于扫描路径，另一组垂直于扫描路径，不管怎样，融和边界不适合于任一组。

对cooper 工具更详细的描述见GAMBIT Modeling Guide 。

你需要把几何体分成许能用cooper 来划分网格的部分。

在GAMBIT 中有许多分解几何体的方法。

在这个例子中，你可以采用把那些挨着弯面的体积部分从主体积中分开的方法。

对这个燃烧室进行分解的详细步骤在下面给出。

注意到几何体中有许多面，其默认的网格划分方案是pave 方案。

这些面中的大部分与Z 方向垂直。

3 模型的网格划分当用户点击Operation工具框中的Mesh命令按钮时，GAMBIT将打开Mesh子工具框。

Mesh子工具框包含的命令按钮允许用户对于包括边界层、边、面、体积和组进行网格划分操作。

与每个Mesh 子工具框命令设置相关的图标如下。

图标命令设置Boundary LayerEdgeFaceVolumeGroup3.1 边界层3.1.1 概述边界层确定在与边和/或者面紧邻的区域的网格节点的步长。

它们用于初步控制网格密度从而控制相交区域计算模型中有效信息的数量。

示例作为边界层应用的一个示例，考虑包括一个代表流体流过管内的圆柱的计算模型。

在正常环境下，很可能在紧靠管道壁面的区域内流体速度梯度很大，而靠近管路中心很小。

通过对壁面加入一个边界层，用户可以增大靠近壁面区域的网格密度并减小靠近圆柱中心的网格密度——从而获得表征两个区域的足够的信息而不过分的增大模型中网格节点的总数。

一般参数要确定一个边界层，用户必须设定以下信息：•边界层附着的边或者面•确定边界层方向的面或者体积•第一列网格单元的高度•确定接下来每一列单元高度的扩大因子•确定边界层厚度的总列数用户还可以设定生成过渡边界层——也就是说，边界层的网格节点类型随着每个后续层而变化。

如果用户设定了这样一个边界层，用户必须同时设定以下信息：•边界层过渡类型•过度的列数3.1.2 边界层命令命令详细说明图标Create Boundary Layer建立附着于一条边或者一个面上的边界层Modify Boundary Layer更改一个现有边界层的定义更改边界层标签Modify Boundary LayerLabelSummarize Boundary在图形窗口中显示现有边界层LayersDelete Boundary Layers删除边界层生成边界层Create Boundary Layer命令允许用户在一条边或者一个面附近定义网格节点步长。

要生成一个边界层，用户必须设定以下参数：•定义•过渡特性•附着实体和方向设定边界层定义要定一边界层，用户必须设定两类特征：•尺寸•内部连续性•角形状尺寸特征包括诸如边界层列数以及第一列高度等因数。

gambit学习手记gambit学习手记（转贴朋友总结的）为表示对这个论坛的支持！今天把USER'S GUIDE 一章发上来，以后陆续会把其他的发上来USER'S GUIDE{1}introduction一.format1.Graphic format1）Control elementsallow you to perform operations such as executing actions and operations, choosing from amon g a given set of options, and inputting alphanumeric data2）toolpad command buttonslocated on the upper and lower right portions of the GUI/doc/2215878243.html,yout format二.font{2}STARTING GAMBIT一.Startup Command Options1）gambit -doc 启动本地网页浏览器打开用户手册 >example:gambit -doc2）gambit -help 显示可用的启动选项 >example:gambit -help3) gambit -dev (driver)4) gambit -def (filename)5) gambit -geom 按像素定义启动窗口大小 >example:gambit -geom 1000 8006）gambit -id (id) >example:gambit系统此时会以默认的default_id给文件一个标识or: gambit -id jxw7) gambit -in (filename)8) gambit -res (filename)9) gambit -new(默认的启动方式都是新文件）>example: gambit -id jxw -new=gambit -id jxw10)gambit -old >example: gambit -id gambit_data/3_pipe -old note: gambit_data目录必须在ntx86二.GAMBIT File Organization1)Session Files.jou.trn.dbs2)Directory Structureworking Directory 存放.jou .trn .dbs文件的临时目录，程序保存退出后删除Source Directory 与gambit启动目录是相同的位置，如d:\gambit_v1.3\ntbin\ntx86\Scratch Directory 与gambit启动目录是相同的位置，如d:\gambit_v1.3\ntbin\ntx86\home Directory{3}GUI一.GUI Components二.GUI Control Elements三.Using the Mouse1）mouse on "Menus and forms " require only left and right buttonsleft button:Open the menu associated with an item on the main menu barSelect a menu commandExecute the operation indicated on a command buttonSelect an option from a list of mutually exclusive radiobuttonsOpen the hidden menu for an option buttonSelect an option from an option-button menuOpen or close a pick-list formEnable a text box for entering dataHighlight an item in a listRelocate (drag) a form on the GUIright button:Open a menu of options available by means of a multifunction toolpad command buttonOpen a hidden menu of options2）Graphics Window 在图形窗口鼠标可以完成三种任务a)产生VERTEXCtrl-right-clickb)显示图形Rotate Left-drag，绕着在屏幕平面上的某个轴旋转，那个轴是于鼠标的移动方向垂直的。

第一章Gambit使用1.1Gambit介绍网格的划分使用Gambit软件，首先要启动Gambit，在Dos下输入Gambit <filemane>，文件名如果已经存在，要加上参数-old。

一．Gambit的操作界面图1 Gambit操作界面如图1所示，Gambit用户界面可分为7个部分，分别为：菜单栏、视图、命令面板、命令显示窗、命令解释窗、命令输入窗和视图控制面板。

文件栏文件栏位于操作界面的上方，其最常用的功能就是File命令下的New、Open、Save、Save as和Export等命令。

这些命令的使用和一般的软件一样。

Gambit可识别的文件后缀为.dbs，而要将Gambit中建立的网格模型调入Fluent使用，则需要将其输出为.msh文件(file/export)。

视图和视图控制面板Gambit中可显示四个视图，以便于建立三维模型。

同时我们也可以只显示一个视图。

视图的坐标轴由视图控制面板来决定。

图2显示的是视图控制面板。

图2 视图控制面板视图控制面板中的命令可分为两个部分，上面的一排四个图标表示的是四个视图，当激活视图图标时，视图控制面板中下方十个命令才会作用于该视图。

视图控制面板中常用的命令有：全图显示、选择显示视图、选择视图坐标、同时，我们还可以使用鼠标来控制视图中的模型显示。

其中按住左键拖曳鼠标可以旋转视图，按住中键拖动鼠标则可以在视图中移动物体，按住右键上下拖动鼠标可以缩放视图中的物体。

命令面板命令面板是Gambit的核心部分，通过命令面板上的命令图标，我们可以完成绝大部分网格划分的工作。

图3显示的就是Gambit的命令面板。

图3 Gambit的命令面板从命令面板中我们就可以看出，网格划分的工作可分为三个步骤：一是建立模型，二是划分网格，三是定义边界。

这三个部分分别对应着Operation区域中的前三个命令按钮Geometry(几何体)、mesh（网格）和Zones（区域）。

generalized additive model (gam)1. 引言1.1 概述在现实生活中，我们经常需要通过建立统计模型来对各种问题进行预测和解释。

然而，传统的线性模型往往无法准确地拟合复杂的非线性关系。

为了克服这个问题，广义可加模型（Generalized Additive Model, GAM）应运而生。

GAM是一种灵活的非参数统计模型，通过将多个光滑函数组合在一起，能够更好地捕捉变量之间的非线性关系。

与传统的线性回归模型相比，GAM不再依赖于线性假设，可以更准确地对数据进行建模和预测。

1.2 文章结构本文将对GAM进行深入探讨。

首先，在第2部分中，我们将介绍GAM的定义和原理，并探讨其在不同领域中的应用情况。

然后，在第3部分中，我们将详细讨论GAM模型的主要组成部分，包括广义可加性假设、成分变量和光滑函数以及模型参数估计方法等。

接下来，在第4部分中，我们将通过实际案例分析来展示如何应用GAM进行数据建模和解释结果。

最后，在第5部分中，我们将总结本文的主要发现，并展望未来研究方向。

1.3 目的本文的目的是介绍GAM这一强大的统计建模工具，并展示其在实际应用中的优势和局限性。

通过深入理解GAM的原理和应用方法，读者可以更好地掌握GAM 模型在数据分析与预测中的作用，为实际问题提供更准确、更可靠的解决方案。

同时，我们还将展望未来有关GAM领域的研究方向，以推动该领域更加广泛和深入的发展。

2. Generalized Additive Model (GAM)2.1 定义和原理广义可加模型（Generalized Additive Model，简称GAM）是一种灵活的非线性统计模型，由各个部分函数的和构成。

它是从广义线性模型（Generalized Linear Model，简称GLM）扩展而来的。

GAM可以捕捉自变量与因变量之间的非线性关系，同时允许控制其他协变量的影响。

GAM采用一个附加到线性预测器上的非参数光滑函数来描述自变量与因变量之间的关系。

3.2 GUI控制单元（GUI Control Elements）下面部分将对上面提到的每个控制单元的意义和操作进行描述。

3.2.1 命令按钮（Command Buttons）命令按钮用来执行程序操作。

这里有两种类型的命令按钮：工具箱型（toolpad）和对话框型（form）。

下表给出了每种命令按钮的例子。

工具箱型命令按钮位于Operation工具箱和Global Control工具箱中；对话框型命令按钮位于GAMBIT对话框中（例如，规范对话框）。

要执行任意命令按钮所代表的操作，只需鼠标左击该按钮即可。

工具箱型命令按钮（T oolpad Command Buttons）工具箱型命令按钮用来执行的程序命令包括创建、网格划分、分配区域类型、或者察看模型以及在GUI上各种工作。

一些工具箱型命令按钮会引起直接的操作，另一些则会打开具体的对话框。

每一个工具箱型命令按钮都有一个代表该按钮功能的符号。

任何可以执行多个功能的按钮（多功能命令按钮）在它的左下角都有一个向下的小箭头。

例如，上面所示的Stitch Faces 命令按钮就可以执行如下的功能：●扫描实面●旋转实面●由线框形成实体要执行一个多功能命令按钮上当前显示的符号所代表的命令，鼠标左击按钮即可。

要改变命令按钮的功能，鼠标右击按钮，打开一个可利用的功能的列表，然后用鼠标左击需要的功能项，就把它从列表中选出来了。

对话框型命令按钮（Form Command Buttons）对话框型命令按钮可以用来执行与GAMBIT对话框有关的操作。

每个按钮只有一个名称（例如，Apply、Reset或Close）。

要执行一个对话框型命令按钮上的名称所代表的操作，只需鼠标左击该按钮即可。

3.2.2 选项按钮（Option Buttons）使用选项按钮可以在一个包含相关的，互相排斥的选项的隐藏菜单中进行选择。

它们只出现在规范对话框中，并在按钮面上以一个凸起的小矩形为标志。

选项按钮上的名称代表了当前从隐藏菜单中选择的选项。

GAMBIT 2.3Tutorial GuideMarch 2006Licensee acknowledges that use of Fluent, Inc.’s products can only provide an imprecise estimation of possible future performance and that additional testing and analysis, independent of the Licensor’s products, must be conducted before any product can be finally developed or commercially introduced. As a result, Licensee agrees that it will not rely upon the results of any usage of Fluent, Inc.’s products in determining the final design, composition, or structure of any product.© 2006 by Fluent, IncorporatedAll Rights Reserved. No part of this document may be reproduced or otherwise used in any form without express written permission from Fluent, Incorporated.Airpak, FIDAP, FLUENT, GAMBIT, Icepak, MixSim, and POLYFLOW are registered trademarks of Fluent, Inc.ImageMagick is © 1996 E.I. du Pont de Nemours and Co.All other products or name brands are trademarks of their respective holders.For GAMBIT Technical Support contact information, visit the Fluent, Inc. Web site at .Fluent, IncorporatedCenterra Resource Park10 Cavendish CourtLebanon, NH 03766iiiTABLE OF CONTENTS0. USING THIS TUTORIAL GUIDE.................................................... 0-1 0.1 What’s in This Guide .....................................................................................0-10.2 How to Use This Guide...................................................................................0-20.3 Font Conventions............................................................................................0-30.4 Using the Mouse..............................................................................................0-40.4.1 Menus and Forms .................................................................................0-40.4.2 Graphics Window.................................................................................0-40.5 GUI Components ............................................................................................0-80.5.1 Graphics Window.................................................................................0-90.5.2 Main Menu Bar ....................................................................................0-90.5.3 Operation Toolpad ...............................................................................0-90.5.4 Form Field..........................................................................................0-110.5.5 Global Control Toolpad .....................................................................0-120.5.6 Description Window ..........................................................................0-120.5.7 Transcript Window and Command Text Box ....................................0-121. CREATING AND MESHING BASIC GEOMETRY....................... 1-1 1.1 Prerequisites ....................................................................................................1-11.2 Problem Description.......................................................................................1-21.3 Strategy............................................................................................................1-31.4 Procedure.........................................................................................................1-4Step 1: Create a Brick....................................................................................1-5Step 2: Create an Elliptical Cylinder .............................................................1-8Step 3: Unite the Two Volumes ..................................................................1-10Step 4: Manipulate the Display ...................................................................1-12Step 5: Mesh the Volume ............................................................................1-14Step 6: Examine the Mesh...........................................................................1-16Step 7: Save the Session and Exit GAMBIT...............................................1-201.5 Summary .......................................................................................................1-212. MODELING A MIXING ELBOW (2-D)........................................... 2-1 2.1 Prerequisites ....................................................................................................2-12.2 Problem Description.......................................................................................2-22.3 Strategy............................................................................................................2-32.4 Procedure.........................................................................................................2-4Step 1: Select a Solver...................................................................................2-4Step 2: Create the Initial Vertices..................................................................2-5Step 3: Create Arcs for the Bend of the Mixing Elbow..............................2-10Step 4: Create Straight Edges......................................................................2-13Step 5: Create the Small Pipe for the Mixing Elbow ..................................2-15Step 6: Create Faces From Edges................................................................2-23Table of ContentsivStep 7: Specify the Node Distribution.........................................................2-26Step 8: Create Structured Meshes on Faces ................................................2-34Step 9: Set Boundary Types ........................................................................2-37Step 10: Export the Mesh and Save the Session .........................................2-412.5 Summary .......................................................................................................2-423. MODELING A THREE-PIPE INTERSECTION (3-D) ................... 3-1 3.1 Prerequisites ....................................................................................................3-13.2 Problem Description.......................................................................................3-23.3 Strategy............................................................................................................3-33.4 Procedure.........................................................................................................3-5Step 1: Select a Solver...................................................................................3-5Step 2: Create the Geometry..........................................................................3-5Step 3: Decompose the Geometry .................................................................3-9Step 4: Journal Files ....................................................................................3-19Step 5: Turn Off Automatic Smoothing of the Mesh..................................3-22Step 6: Apply Boundary Layers at Walls ....................................................3-24Step 7: Mesh the Sphere Octant Volume ....................................................3-28Step 8: Mesh the Pipe Volumes ..................................................................3-30Step 9: Examine the Quality of the Mesh....................................................3-41Step 10: Set Boundary Types ......................................................................3-443.5 Summary .......................................................................................................3-494. MODELING A COMBUSTION CHAMBER (3-D) ......................... 4-1 4.1 Prerequisites ....................................................................................................4-14.2 Problem Description.......................................................................................4-24.3 Strategy............................................................................................................4-34.4 Procedure.........................................................................................................4-6Step 1: Select a Solver...................................................................................4-6Step 2: Set the Default Interval Size for Meshing.........................................4-6Step 3: Create Two Cylinders .......................................................................4-8Step 4: Subtract the Small Cylinder From the Large Cylinder ....................4-12Step 5: Shade and Rotate the Display .........................................................4-14Step 6: Remove Three Quarters of the Cylindrical Volume........................4-15Step 7: Create the Chamber of the Burner ..................................................4-18Step 8: Blend the Edges of the Chamber.....................................................4-20Step 9: Decompose the Geometry ...............................................................4-23Step 10: Generate an Unstructured Hexahedral Mesh ................................4-36Step 11: Examine the Quality of the Mesh..................................................4-49Step 12: Set Boundary Types ......................................................................4-53Step 13: Export the Mesh and Save the Session .........................................4-584.5 Summary .......................................................................................................4-59Table of Contentsv5. SEDAN GEOMETRY—VIRTUAL CLEANUP ............................... 5-1 5.1 Prerequisites ....................................................................................................5-15.2 Problem Description.......................................................................................5-25.3 Strategy............................................................................................................5-35.4 Procedure.........................................................................................................5-4Step 1: Select a Solver...................................................................................5-4Step 2: Import the IGES File As-Is ...............................................................5-5Step 3: Reset and Import the IGES File Using Virtual Cleanup ...................5-9Step 4: Eliminate Very Short Edges ............................................................5-12Step 5: Automatically Connec t All Remaining “Duplicate” Edges ............5-16Step 6: Merge Faces ....................................................................................5-18Step 7: Mesh Faces on Car Body ................................................................5-23Step 8: Create a Brick Around the Car Body ..............................................5-26Step 9: Remove Unwanted Geometry .........................................................5-29Step 10: Create Straight Edges on the Symmetry Plane..............................5-30Step 11: Create Faces on the Symmetry Plane ............................................5-35Step 12: Create a Volume............................................................................5-41Step 13: Mesh the Edges .............................................................................5-43Step 14: Mesh the Volume ..........................................................................5-46Step 15: Examine the Volume Mesh...........................................................5-48Step 16: Set Boundary Types ......................................................................5-515.5 Summary .......................................................................................................5-586. SEDAN GEOMETRY—TOLERANT IMPORT.............................. 6-1 6.1 Prerequisites ....................................................................................................6-16.2 Problem Description.......................................................................................6-26.3 Strategy............................................................................................................6-36.4 Procedure.........................................................................................................6-4Step 1: Select a Solver...................................................................................6-4Step 2: Import the IGES File.........................................................................6-5Step 3: Merge Faces ......................................................................................6-8Step 4: Create a Brick Around the Car Body ..............................................6-13Step 5: Remove Unwanted Geometry .........................................................6-16Step 6: Create Straight Edges on the Symmetry Plane................................6-17Step 7: Create Faces on the Symmetry Plane ..............................................6-22Step 8: Create a Volume..............................................................................6-27Step 9: Apply Size Functions to Control Mesh Quality..............................6-29Step 10: Mesh the Volume ..........................................................................6-31Step 11: Examine the Volume Mesh...........................................................6-33Step 12: Set Boundary Types ......................................................................6-36Step 13: Export the Mesh and Save the Session .........................................6-426.5 Summary .......................................................................................................6-43 Table of Contentsvi7. MODELING FLOW IN A TANK...................................................... 7-1 7.1 Prerequisites ....................................................................................................7-17.2 Problem Description.......................................................................................7-27.3 Strategy............................................................................................................7-37.4 Procedure.........................................................................................................7-6Step 1: Select a Solver...................................................................................7-6Step 2: Set the Default Interval Size for Meshing.........................................7-6Step 3: Create Cylinders................................................................................7-8Step 4: Complete the Geometry Creation....................................................7-12Step 5: Decompose the Geometry ...............................................................7-16Step 6: Unite Some Parts of the Geometry..................................................7-23Step 7: Subtract the Remaining Parts of the Symmetry Plane.....................7-26Step 8: Split off Annulus Pipe to Make the Volumes Meshable.................7-31Step 9: Unite the Side Pipe..........................................................................7-40Step 10: Mesh the Edges .............................................................................7-42Step 11: Apply Boundary Layers ................................................................7-45Step 12: Mesh One of the Volumes ............................................................7-49Step 13: Mesh Some Faces..........................................................................7-52Step 14: Modify Mesh Settings on Some Faces..........................................7-58Step 15: Mesh the Volumes ........................................................................7-61Step 16: Examine the Volume Mesh...........................................................7-66Step 17: Set Zone Types and Export the Mesh ...........................................7-687.5 Summary .......................................................................................................7-738. BASIC TURBO MODEL WITH UNSTRUCTURED MESH.......... 8-1 8.1 Prerequisites ....................................................................................................8-18.2 Problem Description.......................................................................................8-28.3 Strategy............................................................................................................8-48.4 Procedure.........................................................................................................8-5 Step 1: Select a Solver...................................................................................8-5Step 2: Import a Turbo Data File...................................................................8-6Step 3: Create the Turbo Profile....................................................................8-8Step 4: Modify the Inlet and Outlet Vertex Locations ................................8-12Step 5: Create the Turbo Volume................................................................8-14Step 6: Define the Turbo Zones ..................................................................8-16Step 7: Apply 3-D Boundary Layers ...........................................................8-18Step 8: Mesh the Blade Cross-Section Edges .............................................8-22Step 9: Mesh the Center Spanwise Face .....................................................8-26Step 10: Mesh the Volumes ........................................................................8-28Step 11: Examine the Mesh.........................................................................8-30Step 12: Specify Zone Types.......................................................................8-35Step 13: Export the Mesh and Exit GAMBIT.............................................8-368.5 Summary .......................................................................................................8-37 Table of Contentsvii9. LOW-SPEED CENTRIFUGAL COMPRESSOR............................. 9-1 9.1 Prerequisites ....................................................................................................9-19.2 Problem Description.......................................................................................9-29.3 Strategy............................................................................................................9-39.4 Procedure.........................................................................................................9-4 Step 1: Select a Solver...................................................................................9-4Step 2: Import ACIS Geometry.....................................................................9-5Step 3: Create the Turbo Profile....................................................................9-8Step 4: Modify the Inlet and Outlet Vertex Locations ................................9-11Step 5: Create the Turbo Volume................................................................9-13Step 6: Define the Turbo Zones ..................................................................9-15Step 7: Adjust Edge Split Points .................................................................9-17Step 8: Decompose the Turbo Volume .......................................................9-20Step 9: Mesh the Volumes ..........................................................................9-21Step 10: Examine the Mesh.........................................................................9-23Step 11: Specify Zone Types.......................................................................9-27Step 12: Export the Mesh and Exit GAMBIT.............................................9-289.5 Summary .......................................................................................................9-2910. MIXED-FLOW PUMP IMPELLER.............................................. 10-1 10.1 Prerequisites ................................................................................................10-1 10.2 Problem Description...................................................................................10-210.3 Strategy........................................................................................................10-3 10.4 Procedure.....................................................................................................10-4 Step 1: Select a Solver.................................................................................10-4Step 2: Import a Turbo Data File.................................................................10-5Step 3: Create the Turbo Profile..................................................................10-8Step 4: Modify the Inlet and Outlet Vertex Locations ..............................10-11Step 5: Create the Turbo Volume..............................................................10-13Step 6: Define the Turbo Zones ................................................................10-15Step 7: Apply 3-D Boundary Layers .........................................................10-16Step 8: Mesh the Pressure and Suction Faces ...........................................10-19Step 9: Mesh the Volume ..........................................................................10-21Step 10: Examine the Mesh.......................................................................10-23Step 11: Specify or Check Zone Types .....................................................10-28Step 12: Export the Mesh and Exit GAMBIT...........................................10-3010.5 Summary ...................................................................................................10-3111. INDUSTRIAL DRILL BIT—STEP GEOMETRY....................... 11-1 11.1 Prerequisites ................................................................................................11-1 11.2 Problem Description...................................................................................11-211.3 Strategy........................................................................................................11-4 11.4 Procedure.....................................................................................................11-5 Table of ContentsviiiStep 1: Select a Solver.................................................................................11-5Step 2: Import a STEP File .........................................................................11-6Step 3: Merge Faces and Edges to Suppress Model Features .....................11-9Step 4: Use Cleanup Tools to Check and Clean Up Geometry.................11-11Step 5: Apply Size Functions to Control Mesh Quality............................11-18Step 6: Mesh the Volume ..........................................................................11-20Step 7: Examine the Volume Mesh...........................................................11-22Step 8: Export the Mesh and Exit GAMBIT.............................................11-2511.5 Summary ...................................................................................................11-2612. INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT ............... 12-1 12.1 Prerequisites ................................................................................................12-1 12.2 Problem Description...................................................................................12-212.3 Strategy........................................................................................................12-4 12.4 Procedure.....................................................................................................12-5 Step 1: Start Pro/ENGINEER .....................................................................12-5Step 2: Start GAMBIT from within Pro/ENGINEER.................................12-6Step 3: Open the Part File ...........................................................................12-7Step 4: Display the GAMBIT User Interface..............................................12-8Step 5: Select the Solver..............................................................................12-9Step 6: Import the CAD Geometry............................................................12-10Step 7: Merge Faces and Edges to Suppress Model Features ...................12-12Step 8: Use Cleanup Tools to Check and Clean Up Geometry.................12-14Step 9: Apply Size Functions to Control Mesh Quality............................12-26Step 10: Mesh the Volume ........................................................................12-28Step 11: Examine the Volume Mesh.........................................................12-30Step 12: Export the Mesh and Close GAMBIT ........................................12-33Step 13: Exit Pro/ENGINEER and GAMBIT...........................................12-3512.5 Summary ...................................................................................................12-3613. CATALYTIC CONVERTER ......................................................... 13-1 13.1 Prerequisites ................................................................................................13-113.2 Problem Description...................................................................................13-213.3 Strategy........................................................................................................13-313.4 Procedure.....................................................................................................13-4Step 1: Select a Solver.................................................................................13-4Step 2: Import the IGES File.......................................................................13-5Step 3: Attempt to Heal the Geometry ........................................................13-8Step 4: Eliminate the Bad and Overlapping Faces ....................................13-11Step 5: Replace the Overlapping Face ......................................................13-13Step 6: Attempt Again to Heal the Geometry............................................13-15Step 7: Clean Up Holes in the Model........................................................13-17Step 8: Clean Up Short Edges ...................................................................13-21Step 9: Clean Up Sharp Angles.................................................................13-23Table of ContentsixStep 10: Clean Up Large Angles...............................................................13-26Step 11: Stitch the Faces to Create a Volume ...........................................13-29Step 12: Mesh the Large Circular Faces ...................................................13-30Step 13: Apply Size Functions to Control Mesh Quality..........................13-33Step 14: Mesh the Volume ........................................................................13-35Step 15: Examine the Volume Mesh.........................................................13-37Step 16: Export the Mesh and Save the Session .......................................13-4113.5 Summary ...................................................................................................13-4214. AIRPLANE GEOMETRY.............................................................. 14-1 14.1 Prerequisites ................................................................................................14-114.2 Problem Description...................................................................................14-214.3 Strategy........................................................................................................14-314.4 Procedure.....................................................................................................14-4Step 1: Select a Solver.................................................................................14-4Step 2: Import the STEP File ......................................................................14-5Step 3: Clean Up Duplicate Faces...............................................................14-8Step 4: View List of Duplicate Edges .......................................................14-11Step 5: Heal the Geometry ........................................................................14-12Step 6: Clean Up Holes .............................................................................14-13Step 7: Create a Brick around the Airplane Body.....................................14-17Step 8: Delete the Brick High-level Geometry..........................................14-20Step 9: Connect Faces on the Symmetry Plane .........................................14-21。

Tutorial:Geometric Clean-up and HexCore Meshing of an Automotive ManifoldIntroductionThe purpose of this tutorial is to demonstrate the working of the HexCore volume meshing scheme in GAMBIT using an automotive manifold.The HexCore meshing scheme is useful for efficient meshing of volumes containing significant open space with complex wall geometry.This scheme creates an inner region composed of regular hexahedral elements and an outer region consisting of pyramidal,tetrahedral or wedge elements.The hexahedral-element core significantly reduces the total number of elements for the mesh relative to a pure tetrahedral mesh.For more information,refer to Section3.4:Volume Meshing Commands of the GAMBIT Modeling Guide.In this tutorial,you will learn how to:•Import the CAD geometry for an automotive manifold using tolerant modeling.•Extract the virtualflow volume using virtual geometry operations and clean-up tools.•Eliminate sharp angles and short edges using the clean-up tool.•Decompose the virtualflow volume into sections for volume meshing.This will allowthe use of the Cooper meshing scheme on the simple outlet pipes of the manifold,andthe HexCore scheme on the complex central section.•Generate a high quality,low cell count mesh using the HexCore and Cooper meshingschemes for transient performance co-simulation with1D system code.•Use boundary layers and size functions in conjunction with the HexCore and Coopermeshing schemes to create afiner mesh with optimal cell count that can be used foraccurate computation of turbulent heat transfer at the wall.•Activate and use the Tgrid Hexcore scheme with different parameters to generatehexcore meshes.PrerequisitesThis tutorial assumes that you are familiar with the GAMBIT interface and you have worked with CAD geometry.Some steps will not be shown explicitly.If you have not used GAMBIT before,refer to the GAMBIT User’s Guide.GAMBIT User’s Guide,GAMBIT Tutorial Guide, and GAMBIT Modeling Guide.It would be helpful to refer to the introductory training lectures CAD/CAE Data Exchange and Geometry Cleanup(Virtual Operations)and Clean-Up Tools.Geometric Clean-up and HexCore Meshing of an Automotive ManifoldProblem DescriptionThe schematic of the problem is shown in Figure1.The aim of this exercise is to generatea mesh for CFD analysis offlow distribution through an automotive manifold.The CADmodel of an automotive manifold contains solid parts and small features.Theflow volume for CFD analysis has to be extracted from the solid model and cleaned up to yield a high quality mesh.Figure1:Schematic of the Automotive ManifoldThe meshing of the exhaust manifold depends on the requirements of the CFD analysis.The automotive exhaust manifold is part of a larger system whose behavior is simulated in transient mode,using a1D system level code coupled with CFD simulation of the manifold performance.In this case,since the CFD analysis captures the overall transient performance of the manifold,a high quality coarse mesh with low cell count is used.The HexCore meshing scheme can yield a high quality,low cell count mesh with minimum effort.CFD analysis is also used to determine the heat transfer characteristics of the manifold in steady stateflow of exhaust gases.Here the turbulent boundary layer on the manifold walls has to be resolved accurately,especially at the junction of the three manifold inlet pipes.The Boundary Layer and Size Function tools in GAMBIT can be used to grow a high quality fine mesh that adequately resolves the heat transfer characteristics.The HexCore meshing scheme is used to mesh the rest of the volume.This will yield a high quality mesh with optimal cell count that adequately resolves theflow physics in critical areas of the geometry.In this tutorial,both the simple mesh for transient co-simulation and thefiner mesh for heat transfer analysis are generated.A new hexcore meshing method,the TGrid Hexcore,has been introduced in GAMBIT2.3.This method allows the creation of high quality hexcore meshes on highly complexgeometry without the use of size functions to control the volume mesh.In thefinal step inGeometric Clean-up and HexCore Meshing of an Automotive Manifold this tutorial,we will activate the TGrid Hexcore method and use it to mesh the manifold geometry.Geometry Setup and Mesh GenerationStep1:Import the CAD Geometry into GAMBIT1.Start GAMBIT.2.Import the manifold.igsfile.File−→Import−→IGES...(a)Click Browse...and select manifold.igsfile.(b)Ensure that Spatial Translator and Make Tolerant are enabled for Import Options.(c)Enable No stand-alone vertices and No stand-alone edges for Stand-alone Geometry.(d)Ensure that the Heal Geometry and Virtual Cleanup are disabled.(e)Click Accept to import thefile.Geometric Clean-up and HexCore Meshing of an Automotive Manifold Step2:Create the Virtual Flow Volume1.Delete the solid volume.Operation−→Geometry−→Volume−→Delete Volumes(a)Disable the Lower Geometry option.(b)Select volume.1from the selection list and click Apply.(c)Close the Delete Volumes form.2.Delete faces around the manifold inlet and outlet.(a)Set the view as+Z.Operation−→Geometry−→Face−→Delete Faces(b)Select the faces at the inlet and outlet by drawing selection boxes in the upwarddiagonal direction as shown in the Figure2.Hint:For selecting the objects in the Graphic Display Area,left-click and drag an upward diagonal rectangle while the shift key is held down.(c)Click Apply and close the Delete Faces form.Figure2:Positions of the Selection Boxes to Delete Faces Around Inlet and Outlets3.Close all the holes in the geometry.Geometric Clean-up and HexCore Meshing of an Automotive Manifold(a)Click the SPECIFY COLOR MODE button in Global Control toolpad to toggle thecolor mode to connectivity based coloring.Change the view of the model by rotating it slightly to see the holes indicated in orange.Operation−→Tools−→Geometry Cleanup−→Cleanup Holes(b)Disable Auto for Zoom.(c)Click the Auto button and close the form.(d)Click the SPECIFY COLOR MODE button in Global Control toolpad to toggle thecolor mode back to geometric hierarchy based coloring.4.Stitch together theflow volume.Operation−→Geometry−→Volume−→Stitch Faces(a)Select one of the inlet faces(Figure3).Figure3:Inlet FacesNote:Ensure that you have not selected the top face of theflange which sur-rounds the inlet face.(b)Click Apply and close the Stitch Faces form.All other faces will be selected automatically and a real volume will be formed.5.Delete all the faces not belonging to the model.Operation−→Geometry−→Face−→Delete FacesGeometric Clean-up and HexCore Meshing of an Automotive Manifold(a)Select all the faces and click Apply.Theflow volume is now extracted(See Figure4.)(b)Close the Delete Faces form.Figure4:Flow VolumeGeometric Clean-up and HexCore Meshing of an Automotive ManifoldStep3:Clean-up the Virtual Flow Volume1.Remove all small objects.Since all the small details are clustered in the same area,they can be removed easily using global face merge function.(a)Change the view to+Y and zoom in the middle part of the model.Operation−→Geometry−→Face−→Merge Faces(b)Enable Merge edges.(c)Select thefirst group of faces for face merge using an upward diagonal selectionat one of the locations shown in Figure5and click Apply.(d)Repeat the same process at three other locations as shown in Figure5.(e)Change the view to+Z and zoom out to see the entire model.(f)Select thefirst group of faces on left side of the manifold using downward diagonalselections in the direction as shown in Figure6.(g)Repeat the face merge operation at three other locations as shown in Figure6.(h)Zoom into the central section of the geometry.(i)Select the faces at the bottom section of the geometry using downward diagonalselections in the direction as shown in Figure7and click Apply.(j)Repeat the face merge operation at the top using the downward selection rect-angle in the direction as shown in Figure7.Figure5:Selection Boxes for Merging Small Faces(k)Close the Merge Faces form.Geometric Clean-up and HexCore Meshing of an Automotive ManifoldFigure6:Selection Boxes for Merging Small FacesFigure7:Selection Boxes for Merging Small FacesGeometric Clean-up and HexCore Meshing of an Automotive ManifoldStep4:Decompose the Model for Meshinge existing edges to create faces for splitting.(a)Change the view to+Z and zoom in the middle part of the model.(b)Open the Create Face From Wireframe form.Operation−→Geometry−→Face−→Create Face from Wireframe(c)Select Virtual for Type.(d)Select the edges at the left side by a downward diagonal selection in the directionand location shown in Figure8and click Apply.(e)Repeat the same process at the right side at the location shown in Figure8andclose the Create Face from Wireframe form.Figure8:Selection Boxes for Virtual Volume Split Operations2.Split the volume using the created faces.Operation−→Geometry−→Volume−→Split Volume(a)Select Faces(Virtual)for Split With.(b)Select theflow volume(v volume.2).(c)Select the right internal face created in the last step by using an upward diagonalselection as shown in Figure8and click Apply.Theflow volume will be split into two virtual volumes.(d)Select the left volume(v volume.4).(e)Select the left internal face created in the last step by an upward diagonal selec-tion as shown in the Figure8and click Apply.Geometric Clean-up and HexCore Meshing of an Automotive Manifold(f)Close the Split Volume form.Step5:Mesh the Flow Volumes(for a High Quality Low Cell Count Mesh) You will mesh theflow volumes with the HexCore and Cooper Meshing Schemes to get a high quality high quality low cell count mesh.1.Mesh the two outer volumes using the Cooper meshing scheme.Operation−→Mesh−→Volume−→Mesh Volume(a)Select the two volumes having the outlet pipes(v volume.3,v volume.5).(b)Select Cooper for Type.(c)Set the Interval size to0.2and click Apply.GAMBIT creates meshes in the left and right hand side volumes with significantlydifferent cell counts even though the two volumes are identical.This is possible becausethe Cooper tool works by projecting a face mesh on a source face through the volume.Each of the two volumes has two source faces capping the ends:a small inner face anda larger outer face.GAMBIT selects one of them for face meshing using the specifiedInterval size and then projects the face mesh during Cooper meshing.You can avoidthis by premeshing source faces of the same size on each volume.2.Mesh the central volume with HexCore meshing tool.(a)Select the central volume(v volume.6).(b)Select Hexcore for Type.(c)Set the Interval size to0.2and click Apply.3.Examine the volume mesh using the Examine Mesh tool.Display the hex,tet,andpyramid cells and determine the maximum skewness for each.4.Close the Mesh Volumes form.The mesh generated will contain approximately25,500cells with a maximum skewnessof around0.6.A tetrahedral mesh generated with the same size parameter will containapproximately43,000cells with maximum skewness slightly greater than0.75.Step6:Mesh the Flow Volumes(for a High Quality Fine Mesh)You will use boundary layers and size function with the HexCore and Cooper Meshing Schemes to get afine mesh.1.Change the GAMBIT default settings for the boundary layer mesh and the HexCoremeshing scheme.Edit−→Defaults...(a)Click the MESH tab and select BLAYER.You have to scroll down the sidebar to view the BLAYER option.(b)Select USE FACET EVALS from the Variable list.(c)Set the Value to0and click Modify.Setting the value of USE FACET EVALS to zero ensures that the the boundary layer uses an exact representation of the geometry surface from which it is grown.GAMBIT uses the faceted representation of the geometry with the default value of1.(d)Click the MESH tab and select Cartesian.(e)Ensure that the Value of HEXCORE QUAD SURFACE SPLIT is set to1(f)Set the value of HEXCORE OFFSET LAYERS to5.(g)Close the Edit Defaults form.When the value of HEXCORE QUAD SURFACE SPLIT is set to1,the surface quadri-laterals on the HexCore mesh are split into two triangles using a hanging edge.This will ensure that there are no transitional pyramids between the HexCore mesh and the tetrahedral mesh at the boundary.HEXCORE OFFSET LAYERS sets the number of tetrahedral cells between the HexCore mesh and the surface of the volume.If a3D prismatic boundary layer is grown from the surface,then this default sets the number of tets between the HexCore and the boundary layer cap,i.e.,the outer surface of the boundary layer.In this case,there will be a minimum offive layers of tetrahedral between the HexCore mesh and the outermost layer of the3D boundary layer that will be attached to the surface of the volume in the next step.2.Attach a mesh boundary layer to the walls of the volume to resolve the wall effectson turbulence and heat transfer.Operation−→Mesh−→Boundary Layer−→Create Boundary Layer(a)Enter0.03for First row,1.2for Growth Rate,and3for Number of Rows.(b)Enable Internal Continuity.(c)Select Faces for Attachment and select all the lateral faces forming the walls ofthe manifold.(d)Click Apply to create the boundary layer.(e)Close the Create Boundary Layer form.3.Attach a curvature size function to get high resolution of the mesh around bends andjunctions.Operation−→Tools−→Size Function−→Create Size Function(a)Select Curvature for Type.(b)Enter20for Angle,1.1for Growth Rate,and0.2for Size Limit.(c)Select the lateral face of the central volume for Source and select the centralvolume for Attachment in the Entities group box.(d)Click Apply and close the Create Size Function form.Figure9:Cross section of hexcore meshA cross section of the hexcore mesh is seen in Figure9.This mesh has a total of106,00cells and has a maximum skewness of0.754.A full tetrahedral mesh for this geometry with the same quality would contain approximately181000cells.4.Mesh the central volume(v volume6)using the HexCore meshing scheme.5.Mesh the lateral faces of the right and left arm volumes of the manifold individuallyusing the periodic Quad Map scheme with the Proj Intervals set to20.This will resolve the mesh sufficiently along the arms and prevent large size variations in the mesh.6.Mesh the right and left arm volumes using the Cooper scheme.7.Examine the mesh for quality of the volume elements.Step7:Remesh the central volume using the TGrid Hexcore methodA new type of Hexcore meshing method,the TGrid Hexcore method,has been introduced in GAMBIT2.3.This is in addition to the native Hexcore method which was present in earlier versions,and was used in Steps5and6.The TGrid Hexcore method can be enabled by setting the value of the default HEX-CORE METHOD in the Cartesian tab to1.The TGrid Hexcore method does not employ size functions to control the gradation in size in the hexcore.Instead,it uses two additional input parameters,which are enabled in the Hexcore Volume Meshing Form:Buffer Layers and Size Limit.They are displayed in the Mesh Volumes form regardless of the specified Hexcore method,but GAMBIT ignores their values when using the GAMBIT native method. The Buffer Layers value controls the transition between thefine hex mesh near the boundary to the coarser hex mesh in the center of the volume.The Size Limit value determines the maximum element size in the core.It can be specified using the Auto option or the Manual option.The Auto option allows GAMBIT to automatically calculate and set the maximum element size.The Manual option will use the number specified in the text box next to the option.The TGrid Hexcore method is also governed by a default called HEXCORE PEEL LAYERS, which sets the number of layers to be removed from boundary,i.e.,the number of layers of tetrahedrons between the surface mesh or boundary layer cap and the hex core.It is nominally set to a value of1.This is similar to the HEXCORE OFFSET LAYERS default. In this section,we will enable the TGrid Hexcore method and set the values of HEX-CORE PEEL LAYERS,Buffer Layers and Size Limit and remesh the volume.1.Enable the TGrid Hexcore Method by setting the value of HEXCORE METHOD to1.Edit−→Defaults...2.Remesh the central volume v volume.6with the hexcore scheme,using the defaultsettings for Buffer Layers and Size Limit.Operation−→Mesh−→Volume−→Mesh Volume(a)Enable Remove Lower Mesh.(b)Disable Spacing and click Apply.The resulting volume mesh contains368,000cells with a maximum skewness of0.94.The default value of Buffer Layers is1and Size limit is set to Auto.A crosssection of the mesh generated in the central volume using the TGrid HexCoremethod is seen in Figure10.The default settings for Buffer Layers and Size Limitare used.Figure10:Cross section of mesh generated using TGrid Hexcore method with default values of Buffer Layers and Size Limit(c)Now change the values for Buffer Layers and Size Limit and remesh the volume.i.Select v volume.6and enable Remove Lower Mesh.ii.Disable the Spacing option.iii.Set Buffer Layers to2.iv.Select the Manual option for Size Limit.v.Set the value of Size Limit to2.vi.Click Apply.The resulting volume mesh contains426,000cells with a maximum skewness of0.92.A cross section of the mesh generated in the central volume using the TGridHexCore method is seen in Figure11.Here the number of Buffer Layers and theSize Limit are both set to a value of2.(d)Close the Mesh Volumes form.Figure11:Cross Section of mesh generated using TGrid Hexcore method with modified values of Buffer Layers and Size LimitSummaryIn this tutorial,the HexCore meshing was used for optimal meshing of an automotive manifold.The manifold geometry was imported in IGESfile format using tolerant modeling. Theflow volume was extracted and cleaned up using the virtual face merge tool in GAMBIT.A high quality low cell count mesh that can be used for transient co-simulation with a1D system code was generated using the HexCore and Cooper meshing tool.This mesh contains approximately25,000cells with a maximum skewness of0.82,whereas a full tetrahedral mesh of the same size would contain approximately43,000cells.A high qualityfine mesh that can be used for detailed analysis offlow and heat transfer was then generated using the HexCore and Cooper schemes.This mesh uses a curvature size function to resolve curvature of the manifold surface and boundary layer meshing forflow and heat transfer effects at the wall.GAMBIT default settings were changed to customize the HexCore mesh and the boundary layer mesh.Thefine mesh contains approximately104,000cells with maximum skewness of0.754.A full tetrahedral mesh of the same quality generated using the same settings would contain approximately181,000cells.Hence,the HexCore meshing scheme creates high quality meshes with lower cell count on complex geometries than tetrahedral ing boundary layer meshing and size functions with HexCore meshing,afine mesh can be generated that resolves geometry curvature and wall effects.The TGrid Hexcore method was then used to generate a hexcore mesh without the use of size functions.The parameters governing the method,Buffer Layers and Size Limit,were varied to get meshes of different sizes.。

第一章介绍本向导的目的在于分类和描述通过GAMBIT GUI有效的操作。

本向导的逻辑结构遵从Operation工具框和与之相关的子工具框。

也就是说，章节、部分和子部分的组织反应了GUI 上命令按钮的层次。

例如，第二章、第三章、第四章和第五章分别阐述了与命令按钮Geometry、Mesh、Zones和Tools相关的操作，它反应了这些命令按钮在Operation工具框中显示的顺序（如图1所示）。

图1－1：Operation工具框类似的，Blend Volumes操作的详细说明在Volume Boolean操作说明之后，因为在Geometry/ Volume子工具框中它的命令按钮工具框位于Boolean命令按钮的右边（如图1－2所示）。

图1－2：Geometry/Volume子工具框1.1格式和字体的规定GAMBIT User's Guide的第一章阐述了用于整个向导的基本格式和字体的规定。

为了方便起见，在此再次说明格式和字体的规定。

1.1.1格式的规定本向导使用两种标准格式。

•图形格式•版面格式图形格式决定了在GAMBIT GUI中用于代表控制单元和命令按钮的符号类型。

版面格式决定了GAMBIT设定窗口的描述结构。

图形格式使用了两种基本类型的用户界面组件。

•控制单元•工具框命令按钮以下的部分详细说明用于整个文件中的规定来阐述上面列举的组件。

控制单元GAMBIT GUI使用诸如命令按钮、选择按钮和文本框等控制单元来使用户进行诸如执行动作、选择选项设置和输入字母数据等操作。

用于本向导的图形格式规定提供了如下的GAMBIT GUI控制单元。

控制单元示例图形格式功能命令按钮Command执行按钮标题所指示的命令。

选择按钮Option 1从互斥选项菜单中选择。

Option 2…文本框Value从键盘上接受字符数据。

窗口标题Heading:指定按钮和选项组的一般功能单选按钮Option从显示的互斥选项菜单中选择。

Gambit简介体建模GAMBIT MODELING GUIDE：2.生成几何结构以下命令在Geometry/Volume子工具框中可用。

命令详细说明图标通过现有的面或者边生成体积 Form Volume生成具有几个基本形状之一的一个体积 Create Volume合并、交叉或者删除体积 Boolean Operations弄圆和/或者修整体积边 Blend Volumes更改体积颜色；更改体积标签 Modify Volume Color Modify Volume Label移动和/或者复制体积；校准体积和相连的Move/Copy Volumes几何结构 Align Volumes分割或者融合体积 Split VolumeMerge Volumes修整实际的体积几何结构的问题；将非实Heal Real Volume际体转换为实体Convert Volumes显示体积摘要信息；检查拓扑结构和几何Summarize Volumes结构的有效性；打开体积查询列表；显示Check Volumes实体总数 Query VolumesTotal Entities1GAMBIT MODELING GUIDE：2.生成几何结构删除实际的或者虚拟的体积 Delete VolumesForm Volume命令按钮允许用户进行以下操作。

操作详细说明图标从现有的一组面生成体积 Stitch Faces通过沿着指定的路径扫描一个面生成一个体积 Sweep Real Faces通过把一个面旋转一个指定的角度生成一个体积 Revolve Real Faces通过一组现有的边生成一个体积 Form Real VolumeFrom Wireframe以下部分将详细说明执行上面列举的操作的步骤和要求的设定。

Stitch Faces命令允许用户从一组现有的平面生成一个体积。

要通过Stitch Faces命令生成一个体积，用户必须设定如下信息：, 构成该体积的侧面的一组面, 体积的类型指定面要缝合面来构成一个体积，用户必须设定构成该体积侧面的一组面。

附录A——虚拟几何结构A.1 简介GAMBIT几何结构操作包含一套完整的分类工具，它允许用户生成和修改固体模型。

它们包括三个基本的实体类型：∙Real∙Virtual∙FacetedReal实体具有自己的几何结构描述——也就是说，它们通过描述它们的位置和形状的数学公式来确定。

Virtual实体没有自己的几何结构的描述——它们而是通过参考一个或者多个实际的实体来派生出它们的几何结构。

Faceted实体参照一个背景网格来确定。

注意：GAMBIT GUI仅仅参照实际的和虚拟的几何结构。

要将GAMBIT几何结构操作用于磨光面的几何结构，用户必须将它作为虚拟几何结构处理。

本附录的目的在于说明实际的和虚拟的几何结构操作之间的基本区别（A.2部分）以及阐述虚拟几何结构的以下特点：∙基本规则（A.3部分）∙操作（A.4部分）∙应用（A.5部分）A.2实际的和虚拟的操作之间的区别GAMBIT几何结构操作有两种基本类型：∙Real∙VirtualReal几何结构操作仅仅对实际的实体进行并且生成的或者更改的也是实际的拓扑实体。

Virtual几何结构操作可以对任意实际的和/或者虚拟的实体组合进行但是生成的或者更改产生的仅为虚拟的实体。

表A－1和表A－2分别列出了一些包含在GAMBIT实际的或者虚拟的几何结构操作中的基本操作。

表A－2：虚拟结合结构操作注意：本附录的全部内容中，拓扑实体的标签符合GAMBIT默认得标签规则。

也就是说，顶点、边、面和体积分别标记为vertex.a、edge.b、face.c和volume.d，其中a、b、c和d 代表整数——例如，vertex.5或者face.12。

虚拟的实体标签与实际的实体的标签类似但是包括前缀“v_”——例如，v_edge.3或者v_volume.9。

A.3 虚拟几何结构基本规则A.3.1 模型前景和背景要理解虚拟几何结构操作的基本目的，考虑两个不同逻辑区域的GAMBIT建模过程是很有效的。