GAMBIT圆圆柱体的高质量网格划分(钱币划分)
第三章 GAMBIT网格划分基础-1
3.1.4 生成体网格 对于三维流动问题，必须生成三维实体网格。Gambit 提 供五种体网格的生成方法。 1、映射网格
对于六面体结构，可以使用映射网格方法直接生成六面体网格。
对于较为复杂的几何形体，必须在划分网格前将其分割为若干个 六面体结构。
2、子映射网格
Gambit 软件的子映射网格划分技术同样适用于体网格。也就是
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3.2.2 显 示的是视图控制面板。 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。
3、自由网格
对于拓扑形状较为复杂的面，可以生成自由网格，用户可以选择
合适的网格类型(三角形或四边)。
3.1.3 边界层网格 CFD 计算对计算网格有特殊的要求，一是考虑到近壁粘 性效应采用较密的贴体网格，二是网格的疏密程度与流场 参数的变化梯度大体一致。 对于面网格，可以设置平行于给定边的边界层网格，可以 指定第二层与第一层的间距比，及总的层数。 对于体网格，也可以设置垂直于壁面方向的边界层，从而 可以划分出高质量的贴体网格。而其它通用的CAE 前处 理器主要是根据结构强度分析的需要而设计的，在结构分 析中不存在边界层问题，因而采用这种工具生成的网格难 以满足CFD 计算要求，而Gambit 软件解决了这个特殊要 求。
第三章 GAMBIT网格划分基础
曹双华 主讲 07/04
结构网格和非结构网格的区别
结构网格就是在一定区域内的网格点可以用统一 的编号，比如三维的网格点可以用连续i，j，k唯 一标志并且可以表达相互之间的位置关系，比较 节约存储空间，利于编程计算，但对复杂流场的 适应性较差。 非结构网格一般是每个单独的网格单元都有独立 的编号，并且最后要附加一个全场的总编号来确 定每个单独网格之间的关系，占用的存储空间较 大，编程比较麻烦，但是对复杂流场的适应性较 好。
gambit连接头网格划分
INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT© Fluent Inc., Mar-06 12-1 12. INDUSTRIAL DRILL BIT—DIRECT CAD IMPORTThis tutorial employs the industrial drill-bit model described in Tutorial 12 to illustrate the advantages of importing geometry directly from a CAD program rather than importing the geometry by means of an intermediate (STEP) file. The directly imported geometry does not include the very short edges that required elimination in Tutorial 12, however, it does include some small faces that must be merged to facilitate meshing.In this tutorial, you will learn how to:• Import geometry directly from the Pro/ENGINEER CAD program• Use the GAMBIT cleanup tools to identify and eliminate geometry features thatcan adversely affect meshing operationsNOTE (1): The capability of direct geometry import from the Pro/ENGINEER program requires a special GAMBIT license. Without the license, GAMBIT cannot open a data-base that includes directly imported CAD geometry. NOTE (2): You can reproduce the perspectives of the figures in this tutorial by means of window matrix commands available in a journal file named “tg12_figures.jou ,” which is included in the “help/tutfiles ” online help directory. To exactly reproduce the perspective of any figure, you must open the journal file and execute the window matrix command associated with the figure. For example, the following command repro-duces the perspective of the model shown in Figure 12-3.window matrix 1 entries \ 0.8298196196556 0.1376460045576 -0.5407903790474 \ -0.98521900177 -0.3953186273575 0.828989803791 \ -0.3955990076065 -0.0812062472105 0.3938567638397 \ 0.5420601963997 0.742325425148 -3.794617891312 \ -12.156******** 12.11377906799 -4.06431388855 \ 15.50736236572 -22.28459358215 22.2845935821512.1 PrerequisitesPrior to reading and performing the steps outlined in this tutorial, you should familiarize yourself with the steps, principles, and procedures described in Tutorials 1, 2, 3, 4, 8, and 11.Problem Description INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT 12-2 © Fluent Inc., Mar-0612.2 Problem DescriptionFigure 12-1 and Figure 12-2 show the drill-bit configuration to be modeled and meshed in this tutorial. Figure 12-1 shows the full model, including the outer face that circumscribes the internal components. Figure 12-2 shows the internal components, themselves. Themodel shown in these figures is identical to that described in Tutorial 11.Figure 12-1: Industrial drill bit configuration—full modelINDUSTRIAL DRILL BIT—DIRECT CAD IMPORT Problem Description© Fluent Inc., Mar-0612-3Figure 12-2: Industrial drill bit configuration—internal componentsThe goals of this tutorial are:• To directly import the drill-bit geometry from the Pro/ENGINEER CAD program • To use GAMBIT cleanup operations to render the model suitable for meshing• To mesh the model using unstructured, tetrahedral mesh elements the quality ofwhich is controlled by means of size functionsThis tutorial, in conjunction with Tutorial 11, also illustrates the differences between direct CAD geometry import and geometry import by means of STEP data files. Specifically, this tutorial imports the data directly from the Pro/ENGINEER program as a “part” file. Consequently, the imported geometry does not include the very short edges that otherwise complicate meshing (see Tutorial 11).Strategy INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT12.3 StrategyThe general strategy employed in this tutorial is as follows:1)Start the Pro/ENGINEER program.2)Launch GAMBIT from within Pro/ENGINEER.3)Import to GAMBIT a Pro/ENGINEER part file that describes the drill-bitgeometry.4)Use GAMBIT cleanup operations to eliminate a few small faces that wouldotherwise complicate meshing.5)Apply size functions to control mesh quality.6)Mesh the model.The operations involved in items 4–6, above, are nearly identical to those described in Steps 4–6 of Tutorial 11.12-4 © Fluent Inc., Mar-06INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT Procedure12.4 ProcedureStep 1: Start Pro/ENGINEER1.In a terminal window, entergambit -id Drill_Bit_ProE –proe proe_startup_command where proe_startup_command is the system-specific command to start Pro/-ENGINEER.This command starts Pro/ENGINEER and displays the Pro/ENGINEER user interface.!GAMBIT is available only in a 32-bit version; therefore, the Pro/ENGINEER version used for direct CAD import must also be 32-bit.© Fluent Inc., Mar-06 12-5Procedure INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT 12-6 © Fluent Inc., Mar-06Step 2: Start GAMBIT from within Pro/ENGINEER1. Start GAMBIT and make it available as an option on the Pro/ENGINEER main menu.a) Open the Pro/ENGINEER Auxiliary Applications form.Tools → Auxiliary Applications…This command sequence opens the Pro/ENGINEER Auxiliary Applicationsform.i. In the list of available auxiliary applications, select gambit , and click Start .Pro/ENGINEER starts GAMBIT and displays a new option—titled,Gambit —on the Pro/ENGINEER main menu. Pro/ENGINEER alsodisplays the message, “Application ‘gambit’ started successfully,” toindicate the successful launch of the GAMBIT program.ii. Click Close to close the Auxiliary Applications form.INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT Procedure © Fluent Inc., Mar-06 12-7 Step 3: Open the Part File1. Open the Pro/ENGINEER part file.a) Open the Pro/ENGINEER part file that describes the drill bit geometry.File → Open…This command sequence opens the Pro/ENGINEER File Openform.i. In the file list, select drill_bit.prt , and click Open .Pro/ENGINEER opens the part file and displays it in the Pro/ENGINEERGUI graphics window.! You cannot operate on parts or assemblies from within Pro/ENGI-NEER while GAMBIT is running.Procedure INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT Step 4: Display the GAMBIT User Interface1.Display the GAMBIT graphical user interface.a)On the Pro/ENGINEER main menu, start the GAMBIT interface.Gambit → StartPro/ENGINEER replaces its foreground user interface with that of GAMBITand remains operational in the background.It is possible to switch between Pro/ENGINEER and GAMBIT operationwhile GAMBIT is running.•To switch from GAMBIT to Pro/ENGINEER, you must exit GAMBIT by means of the File/Close option on the GAMBIT main menu bar.When you exit GAMBIT in this manner, the GAMBIT window isiconized, and GAMBIT continues to run until you end its executionfrom within Pro/ENGINEER.•To switch from Pro/ENGINEER to GAMBIT, select the Gambit→Start option on the Pro/ENGINEER main menu bar.To ensure that any GAMBIT operations are preserved when switching backand forth between GAMBIT and Pro/ENGINEER, it is advisable to save theGAMBIT database before switching from GAMBIT to Pro/ENGINEERoperation.12-8 © Fluent Inc., Mar-06INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT Procedure Step 5: Select the Solver1.Choose the solver from the main menu bar:Solver → FLUENT 5/6The choice of solver affects the types of options available in the SpecifyBoundary Types form. For some systems, FLUENT 5/6 is the default solver. Thecurrently selected solver is shown at the top of the GAMBIT GUI.© Fluent Inc., Mar-06 12-9Procedure INDUSTRIAL DRILL BIT—DIRECT CAD IMPORT 12-10 © Fluent Inc., Mar-06 Step 6: Import the CAD GeometryIn this step, you will directly import the drill-bit geometry from Pro/ENGINEER . GAMBIT designates the imported geometry as “CAD” geometry, and assigns its components a “c_” prefix—for example, c_face.123.! To import geometry directly from Pro/ENGINEER to GAMBIT , you must have aspecial GAMBIT license. Without the license, GAMBIT cannot open a database that includes directly-imported CAD geometry.1. Select the Import CAD Geometry option from the GAMBIT main menu bar.File → Import → CAD...This command sequence opens the Import CAD Geometryform.a) On the CAD Option option button, select the Pro/ENGINEER (DIRECT) option. b) On the Component option button, select the DRILL_BIT.PRT option.The Component option button includes all part files that are currently open in Pro/ENGINEER .2. On the Import CAD Geometry form, click Accept .GAMBIT imports the part file and displays the geometry shown in Figure 12-3.© Fluent Inc., Mar-0612-11Figure 12-3: Industrial drill bit—directly imported Pro/ENGINEER part fileStep 7: Merge Faces and Edges to Suppress Model Features As a first step in improving the meshing characteristics of the model, you will perform global face and edge merge operations to eliminate many faces that could otherwise adversely affect meshing.1.Perform a global face-merge operation.GEOMETRY →FACE → SPLIT/MERGE/COLLAPSE/SIMPLIFY FACES RThis command sequence opens the Merge Faces form.a)On the Type option subset, select the Virtual (Tolerance) option.b)On the Faces pick-list option button, select All.c)In the Min. Angle text box, input 160.d)Retain the Merge edges option.e)Click Apply to merge the faces.GAMBIT merges the faces as shown in Figure 12-4.12-12 © Fluent Inc., Mar-06© Fluent Inc., Mar-0612-13Figure 12-4: Model after face-merge operationStep 8: Use Cleanup Tools to Check and Clean Up Geometry GAMBIT cleanup tools allow you to identify and eliminate individual model features that can inhibit meshing. In this step, you will use the cleanup tools to check for the existence of very short edges, “holes,” “cracks,” and small faces in the model and to eliminate some of the small faces.1.Identify any short edges in the model that might cause meshing problems.TOOLS →CLEANUP →CLEAN UP SHORT EDGESThis command sequence opens the Clean Up Short Edgesform.When you open any of the cleanup forms, such as the Clean Up Short Edges form, GAMBIT automatically sets the graphics window color mode to display colors based on connectivity rather than topology. In addition, GAMBIT automatically sets the graphics window pivot function to the user-specified pivot mode.12-14 © Fluent Inc., Mar-06a)Click the Default pushbutton located on the right side of the Maximum length textbox.GAMBIT displays the Maximum length of edges to be included in the Items listand populates the Items list with all edges in the Cleanup domain that meet theMaximum length criterion. (In this case, the entire model constitutes theCleanup domain.) By default, the Maximum length value is 10 times greaterthan the arc length of the shortest edge in the Cleanup domain.b)Select the first edge in the Items list.GAMBIT displays the arc length of the selected edge in the Current lengthfield located below the Items list and highlights and zooms in on the selectededge in the graphics window (see Figure 12-5).Figure 12-5: Automatic graphics-window display of the first listed edgeIn this case, the shortest edge in the model is not short enough to adverselyaffect meshing.2.Check for the existence of holes in the model.“Holes” in the model are internal edge loops that do not constitute face boundaries.© Fluent Inc., Mar-06 12-15TOOLS →CLEANUP →CLEAN UP HOLESThis command sequence opens the Clean Up Holesform.a)Click the Update pushbutton located on the right side of the Items list heading.In this case, GAMBIT does not populate the Items list, because no holes existin the model.3.Check for the existence of cracks in the model.For the purposes of the geometry cleanup operations, a “crack” is defined as a geometry consisting of an edge pair that meets the following criteria:•Each edge in the pair serves as a boundary edge for a separate face.•The edges share common endpoint vertices at one or both ends.•The edges are separated along their lengths by a small gap.TOOLS →CLEANUP →CLEAN UP CRACKSThis command sequence opens the Clean Up Cracks form.12-16 © Fluent Inc., Mar-06© Fluent Inc., Mar-0612-17a) Click the Default pushbutton located on the right side of the Maximum angle textbox.GAMBIT displays the default Maximum angle criterion and automatically populates the Items list with all cracks existing in the model. In this case, GAMBIT does not populate the Items list, because no cracks exist in the model.4. Clean up one sharp angle in the model.In this substep, you will use the Clean Up Sharp Angles form to identify and eliminate an edge pair that constitutes a “sharp angle.” For the purposes of the geometry cleanup operations, a sharp angle is defined as an edge pair that meets the following criteria:• The edge pair shares a common endpoint vertex and serves as part of theboundary for an existing face.• One of the edges in the sharp-angle edge pair serves as a commonboundary edge between its bounded face and an adjacent face.• The angle between the edges in the pair (computed at their commonendpoint vertex) is less than a specified angle.TOOLS →CLEANUP →CLEAN UP SHARP ANGLESThis command sequence opens the Clean Up Sharp Anglesform.a)Click the Default pushbutton located on the right side of the Maximum angle textbox.GAMBIT displays the Maximum angle of angles to be included in the Items listand populates the Items list with all face-vertex pairs in the Cleanup domainthat meet the Maximum angle criterion. By default, the Maximum angle value is20.b)Select the first face-vertex pair in the Items list.GAMBIT highlights and zooms in on the geometry that constitutes the sharpangle (see Figure 12-6).12-18 © Fluent Inc., Mar-06Sharp angleFigure 12-6: Geometry constituting a sharp angleThe Clean Up Sharp Angles operation uses a Merge faces procedure toeliminate any sharp angle. In this case, GAMBIT automatically populates theFaces to merge pick list with suggested faces to merge and selects the Chopoption. (For a complete description of the Clean Up Sharp Angles form, see“Clean Up Sharp Angles” in Section 5.4.2 of the GAMBIT Modeling Guide.)c)Click the Apply pushbutton in the vertical array of pushbuttons located to the rightof the Items list.GAMBIT merges the highly angular region of one face with the adjacent faceto eliminate the sharp angle (see Figure 12-7).© Fluent Inc., Mar-06 12-19Merged regionFigure 12-7: Geometry after sharp-angle cleanup operation5.Clean up small faces in the model.In this substep, you will use the Clean Up Small Faces form to identify and eliminate individual small faces that can adversely affect meshing operations.TOOLS →CLEANUP →CLEAN UP SMALL FACESThis command sequence opens the Clean Up Small Faces form.12-20 © Fluent Inc., Mar-06© Fluent Inc., Mar-0612-21a) Click the Default pushbutton located on the right side of the Maximum area textbox.GAMBIT displays the Maximum area of faces to be included in the Items list and populates the Items list with all faces in the Cleanup domain that meet the Maximum area criterion. By default, the Maximum area value is 100 times greater than the area of the smallest face in the Cleanup Domain .Figure 12-6 shows the three smallest faces in the model, all of which lie at the base of the main drill-bit shaft. These three faces correspond to the first three labels listed in the Items list.ACBFigure 12-8: Three smallest faces in the modelb)Select the first face in the Items list.GAMBIT displays the area of the selected face in the Current area fieldlocated below the Items list and highlights the selected face (face A in Figure12-8) in the graphics window.The Clean Up Small Faces form provides two Method options for eliminatingfaces—Collapse face and Merge face. In this case, GAMBIT automaticallyselects the Merge face option and populates the Faces to merge pick list withsuggested faces to merge.c)Click the A/N pushbutton in the vertical array of pushbuttons located to the right ofthe Items list.The A/N (“Apply/Next”) pushbutton removes the currently selected face fromthe model, then updates the Items list and automatically selects the nextsmallest face in the Cleanup domain. In this case, GAMBIT eliminates theselected face and automatically selects the next smallest face (face B in Figure12-8).d)Click A/N again to eliminate the next smallest face in the Cleanup domain.12-22 © Fluent Inc., Mar-06GAMBIT eliminates the selected face and automatically highlights the nextsmallest face (face C in Figure 12-8).e)Click Apply to eliminate the third smallest face in the Cleanup domain.Figure 12-9 shows the geometry in the region of the three smallest faces aftertheir removal from the model.Figure 12-9: Geometry with three smallest faces cleaned upHaving eliminated the three small, ovoid faces at the base of the main shaft,you will now remove four small, rectangular faces that serve as lips to other,larger faces (see Figure 12-10).© Fluent Inc., Mar-06 12-23DE FGFigure 12-10: Small, rectangular lip facesf)Select the first face in the Items list.GAMBIT highlights and zooms in on the smallest of the rectangular lip faces(face D in Figure 12-10) and automatically selects the Merge faces option andpopulates the Faces to merge pick list with suggested faces to merge.g)Click the A/N pushbutton to eliminate the selected face and automatically select thenext smallest face (face E in Figure 12-10).h)Click the A/N pushbutton to eliminate the selected face and automatically select thenext smallest face (face F in Figure 12-10).i)Click the A/N pushbutton to eliminate the selected face and automatically select thenext smallest face (face G in Figure 12-10).j)Click Apply to eliminate the last of the lip faces.After cleanup of the last lip face, the Items list still contains a list of smallfaces; however, the remaining faces are not small enough to adversely affectmeshing operations.Figure 12-11 shows the final, cleaned-up geometry.12-24 © Fluent Inc., Mar-06© Fluent Inc., Mar-0612-25Figure 12-11: Final, cleaned-up model geometryStep 9: Apply Size Functions to Control Mesh Quality Highly skewed elements adversely affect numerical computations for which the mesh is created. GAMBIT includes several features that allow you to control the mesh, one of which is the application of size functions. For example, size functions can be used to specify the rate at which volume mesh elements change in size in proximity to a specified boundary. In this step, you will apply size functions to four faces of the drill-bit geometry and, thereby, control the size of the nearby mesh elements to eliminate the skewed elements.1.Specify a size function and apply it to four faces of the model.TOOLS →SIZE FUNCTIONS →CREATE SIZE FUNCTIONThis command sequence opens the Create Size Function form.a)Retain the Type:Fixed option.(NOTE: In addition to the “fixed” size function illustrated in this tutorial,GAMBIT provides “curvature,” “proximity,” and “meshed” size functions.Curvature and proximity size functions are useful for controlling the mesh inregions of high curvature and small gaps, respectively. Meshed size functionsuse existing meshes to determine the size-function start size. See Section 5.2.2of the GAMBIT Modeling Guide.)12-26 © Fluent Inc., Mar-06b)On the Entities:Source option button, select the Faces option.c)In the Faceslist box, select the four faces shown (shaded) in Figure 12-12.d)On the Entities:Attachment option button, select the Volumes option.e)In the Volumes list box, select the volume.f)In the Start size text box, enter the value 0.035.g)In the Growth rate text box, enter the value, 1.2.h)In the Max. size text box, enter the value, 0.4.i)Click Apply to create the size function.© Fluent Inc., Mar-06 12-27Step 10: Mesh the VolumeAfter the imported geometry is cleaned up and the size-function is created and attached, you can mesh the geometry using an unstructured, tetrahedral mesh.1.Mesh the drill-bit volume.MESH →VOLUME →MESH VOLUMESThis command sequence opens the Mesh Volumesform.a)Activate the Volumes list box.b)Select the volume.GAMBIT automatically selects the Scheme:Elements:Tet/Hybrid and Scheme:Type:TGrid options.c)Retain the automatically selected Scheme options.d)On the Spacing option button, retain the Interval size option.12-28 © Fluent Inc., Mar-06e)In the Spacing text box, retain the default value of 1.(NOTE: The size function you attached to the volume in the previous step willoverride the Spacing specifications.)f)Click Apply.Figure 12-13 shows the final meshed volume.Figure 12-13: Meshed drill-bit volume© Fluent Inc., Mar-06 12-29Step 11: Examine the Volume Mesh1.Select the EXAMINE MESHcommand button at the bottom right of the GlobalControl toolpad.This action opens the Examine Meshform.a)Click Update at the bottom of the Examine Mesh form.12-30 © Fluent Inc., Mar-06GAMBIT does not automatically update the graphics display when you open the Examine Mesh form or modify its specifications, such as Display Type or Quality Type. To update the graphics display, you must click the Update push-button located at the bottom of the form. GAMBIT displays the Update pushbutton label in red lettering whenever the display needs to be updated to reflect the current Examine Mesh specifications.Some Examine Mesh operations automatically update the graphics display.For example, if you select the Display Type:Range option and click one of the histogram bars (see below), GAMBIT automatically updates the display.b)Select Range under Display Type at the top of the form.The 3D Element type selected by default at the top of the form is a brick .You will not see any mesh elements in the graphics window when you first open the Examine Mesh form, because there are no hexahedral elements in the mesh.c)Left-click the tetrahedron icon next to 3D Element near the top of the form.The tetrahedral mesh elements will now be visible in the graphics window.d)Select or retain EquiSize Skew from the Quality Type option menu.e)Left-click the histogram bars that appear at the bottom of the Examine Mesh formto highlight elements in any given quality range.Figure 12-14 shows the graphics window that results for elements withEquiSize Skew values between 0.5 and 0.6.© Fluent Inc., Mar-06 12-3112-32© Fluent Inc., Mar-06Figure 12-14: Elements with EquiSize Skew values between 0.5 and 0.6f) On the Examine Mesh form, click Close to close the form.Step 12: Export the Mesh and Close GAMBIT1.Export a mesh file.a)Open the Export Mesh File formFile → Export → Mesh…This command sequence opens the Export Mesh Fileform.iii.Click Accept.GAMBIT writes the mesh file to your working directory.2.Save the GAMBIT session and close GAMBITa)Select Close from the File menu.File → CloseThis command sequence opens the Closeform.© Fluent Inc., Mar-06 12-33The Close option is available only when GAMBIT is launched from within thePro/ENGINEER program.b)Click Yes to save the current session and return to Pro/ENGINEER.The Pro/ENGINEER user interface redisplays in the foreground, andGAMBIT continues to run in the background.12-34 © Fluent Inc., Mar-06Step 13: Exit Pro/ENGINEER and GAMBIT1.Exit the Pro/ENGINEER program.File → Exit…form.This command sequence opens the Pro/ENGINEER CONFIRMATIONa)Click Yes to exit Pro/ENGINEER.When you exit Pro/ENGINEER, GAMBIT is still running, and the Close formis still open.b)On the GAMBIT Close form, click No to exit GAMBIT.© Fluent Inc., Mar-06 12-3512.5 SummaryThis tutorial demonstrates the direct import of CAD geometry into GAMBIT and the operations that are sometimes required to render such geometry amenable to GAMBIT meshing operations. A comparison of the procedures described here with those of Tutorial 11 illustrates the advantages of direct CAD import versus import of CAD geometry by means of intermediate files—for example, STEP files. Specifically, the directly imported geometry does not include the very short edges that result from geometry import by means of the STEP file.12-36 © Fluent Inc., Mar-06。
第二章 Gambit划分网格
1）应用分级设定的边
2）分级方案
3）网格节点步长（间隔数目） 4）边网格划分选项
线网格划分
2）分级方案 Gambit 提供了以下类型的边网格划分分级方案：
• • • • • •
•
Successive Ratio First Length Last Length First Last Ratio Last First Ratio Exponent Bi-exponent Bell Shaped
非对称格式，产生的分级 形式不需要关于边的中心对称
对称格式，限制关于边 中心对称的分级类型
•
线网格划分
• 狭长型网格长宽比不要超过5； • 燃烧反应的区域网格尽量细化。
3、面网格划分
进行一个面网格划分，用户必须 设定以下参数：
1）要网格划分的面
2）网格划分的形式 3）网格节点的间距 4）面网格划分选项
体网格光顺化
• Smooth Volume Meshes 在一个或多个体积上光顺化网格节点。 1、选择要光顺化的体积； 2、光顺化方案 L-W Lapiacian:使每个节点 周围单元平均边长； Equipotential：使节点周围单元体积相等。
体网格划分技巧
• 首先画线网格和部分面网格； • 尽量采用五面体和六面体网格，以控制网 格数量； • 复杂结构考虑分块画网格，避免把所有几 何组合成一个整体；
平整面网格
Smooth Faces Meshes命令 将调整一个或者多个面网格节点的位置 用户需设定以下参数： 1）要平整的网格面 2）平整方式 L-W Laplalian ：在每个节点周围使用单元的平均变长（趋向平 均单元 边长）
Centroid Area ：平衡相邻单元的面积
GAMBIT网格划分 教程详细版
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圆柱绕流的一种网格画法
圆柱绕流的一种网格画法及其应用
1.建立如下模型,将区域划分为四个面.
2.对边划网格,和钱币网格划法相同,对应边网格数相同.
3.对面划网格,采用map结构的四边形网格.
应用
1.在gambit中建立如下模型
2.建立两个面将模型分为四部分.
3.对两边圆弧结构划网格,对应边网格数相同,采用map结构的四边形网格,对体采用cooper方式划网格.如下图所示.
4.对圆柱形区域划网格,先处理,建立如下图所示四个面,将两个体分为8个体,采用上面圆柱绕流网格划法对面划网格,采用cooper方式对体划网格.
5.对于每个已经化为4个体的圆柱形区域，选中四个体直接进行网格划分。
（Hex-Map）。
圆柱绕流问题的三种网格划分
中山大学工学院计算流体力学实验报告实验名称：圆柱绕流问题的三种网格划分姓名：刘广参与组员：刘广学号：11309018任课教师：詹杰民学科专业：工学院理论与应用力学中山大学2014年04月05日图1对于四个面，如图2所示，参数interval count我们选择10，点击apply效果如图3所示。
图2Page 3 of 12图3下面我们对其划分的网格进行质量分析。
点击面板进入网格分析区域，就是Examine Mesh面板当中，Display Type我们选择Rang，2D Element，三角形网格类型，点击下方update 就可以看到如图4所示网格质量图。
图4Page 4 of 12我们继续看图5所示的网格质量分析数据，可以看到，三角形网格一共有1324个，其中在圆柱后方的若干区域网格质量最差。
图5最差质量的网格如图6所示。
图6接下来我们开始介绍矩形网格划分。
如下图7所示；我们首先画四段四分之一圆弧，其中圆弧对应的圆周半径为1.然后我们再绘制如图所示的矩形。
其中外部的矩形长32，宽22，并做如下图所示的划分。
其中详细作图步骤在上次实验报告中有详细叙述，这里不再赘述。
所示图7中有八个面，其中圆形上的点为对圆形进行45度划分。
现在我们选择矩形网格对Page 5 of 12其进行划分，图7对于八个面，如图8所示，参数interval count我们选择10，点击apply效果如图9所示。
图8Page 6 of 12图9下面我们对其划分的网格进行质量分析。
点击面板进入网格分析区域，就是Examine Mesh面板当中，Display Type我们选择Rang，2D Element，矩形网格类型，点击下方update就可以看到如图10所示网格质量图。
图10我们继续看图11所示的网格质量分析数据，可以看到，矩形网格一共有20000个，其中在Page 7 of 12圆柱上方、左方、右方、后方的若干区域网格质量最差。
000-Gambit网格划分(自己重新排版)
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
选择显示项目 渲染方式。
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。
【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1.2显示的是视图控制面板。
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。
在面的创建中，有一个布尔运算的操作，可以使我们创建不规则形状的面（见图1.17）。布尔运算包括三种方式：加、减、交。
三、
在命令面板中单击Mesh按钮，就可以进入网格划分命令面板。在Gambit中，我们可以分别针对边界层、边、面、体和组划分网格。图2.1所示的五个按钮分别对应着这五个命令。
Boundary Layer
图2.8
（三）划分面的网格
Gambit对于二维面的网格的划分提供了三种网格类型：四边形、三角形和四边形/三角形混合，同时还提供了五种网格划分的方法。表1、2分别列举了五种网格划分的方法以及它们的适用类型。
表1
方法
描述
Map
创建四边形的结构性网格
Submap
将一个不规则的区域划分为几个规则区域并分别划分结构性网格。
边上的网格点的分布可分为两种情况，一种是单调递增或单调递减，一种是中间密（疏）两边疏（密）。下面依然结合实例介绍边上网格点的创建。
gambit网格划分的评价标准
如何检查网格质量，用什么指标来说明网格好不好呢？怎么控制？一般是什么原因造成的?一般也就是，网格的角度，网格变形的梯度等等吧判断网格质量的方面有很多，不知你用的是什么软件，下面总结的是针对Gambit帮助文件的简单归纳，不同的软件有不同的评价单元质量的指标，使用时最好仔细阅读帮助文件。
Area单元面积，适用于2D单元，较为基本的单元质量特征。
Aspect Ratio长宽比，不同的网格单元有不同的计算方法，等于1是最好的单元，如正三角形，正四边形，正四面体，正六面体等；一般情况下不要超过5：1.Diagonal Ratio对角线之比，仅适用于四边形和六面体单元，默认是大于或等于1的，该值越高，说明单元越不规则，最好等于1，也就是正四边形或正六面体。
Edge Ratio长边与最短边长度之比，大于或等于1，最好等于1，解释同上。
EquiAngle Skew通过单元夹角计算的歪斜度，在0到1之间，0为质量最好，1为质量最差。
最好是要控制在0到0.4之间。
EquiSize Skew通过单元大小计算的歪斜度，在0到1之间，0为质量最好，1为质量最差。
2D质量好的单元该值最好在0.1以内，3D单元在0.4以内。
MidAngle Skew通过单元边中点连线夹角计算的歪斜度，仅适用于四边形和六面体单元，在0到1之间，0为质量最好，1为质量最差。
Size Change相邻单元大小之比，仅适用于3D单元，最好控制在2以内。
Stretch伸展度。
通过单元的对角线长度与边长计算出来的，仅适用于四边形和六面体单元，在0到1之间，0为质量最好，1为质量最差。
Taper锥度。
仅适用于四边形和六面体单元，在0到1之间，0为质量最好，1为质量最差。
Volume单元体积，仅适用于3D单元，划分网格时应避免出现负体积。
Warpage翘曲。
仅适用于四边形和六面体单元，在0到1之间，0为质量最好，1为质量最差。
另外，在Fluent中的窗口键入：grid quality 然后回车，Fluent能检查网格的质量，主要有以下三个指标：1.Maxium cell squish: 如果该值等于1，表示得到了很坏的单元；2.Maxium cell skewness: 该值在0到1之间，0表示最好，1表示最坏；3.Maxium 'aspect-ratio': 1表示最好。
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1）先在opteration--geometry-volumn中创建了一个高为100，半径15的圆柱体。
然后再圆柱的底面建立了一个边长为8的正方形，将正方形旋转45度，使正方形的一个顶点跟底面圆的点对齐，然后将圆周分割为4等分，将这4个顶点和正方形的四个顶点连成线，效果如图所示：
2）然后用这四条线沿Z轴正向的矢量方向长出4个面，效果如图：
3）用正方形去分割底面圆，注意选择connected选项，再用刚才形成的四个面去分割那个古钱形的底面，把它分成4部分，如果做到这一步，基本难的地方就过去了，效果如图所示：
4)下面就是把对应边划分网格，注意正方形每条边对应的圆弧边划分的网格份数是一样的，效果如图：
5)划分面网格，选择map结构的四边形网格，效果如图:
6)最后划分体网格，按照cooper方式的六面体网格来划分，效果如图：
另附链接：/30181642_d.html。