ANSYS 12.0 官方培訓手冊-Introduction to CFX-PART A

1、TOC-1ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598ANSYS 12.0 Training ManualCFX 12.0Introduction to CFXPart A Chapter 1-3, 106 PagesCFX 12.0 Introductory TrainingTOC-2ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #

2、002598Training ManualInventory Number: 0025981st EditionANSYS Release: 12.0Published Date: April 28, 2009Registered Trademarks:ANSYS is a registered trademark of SAS IP Inc.All other product names mentioned in this manual are trademarks or registered trademarks of their respective manufacturers.Disc

3、laimer Notice:This document has been reviewed and approved in accordance with the ANSYS, Inc. Documentation Review and Approval Procedures. “This ANSYS Inc. software product (the Program) and program documentation (Documentation) are furnished by ANSYS, Inc. under an ANSYS Software License Agreement

4、 that contains provisions concerning non-disclosure, copying, length and nature of use, warranties, disclaimers and remedies, and other provisions. The Program and Documentation may be used or copied only in accordance with the terms of that License Agreement.”Copyright 2009 SAS IP, Inc.Proprietary

5、data. Unauthorized use, distribution, or duplication is prohibited.All Rights Reserved.CFX 12.0 Introductory TrainingTOC-3ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualAgenda: Day 18:30 8:40Welcome8:40 9:00Introduction to CFD9:00 9:45CFX G

6、UI and Workflow Demo9:45 10:45Workshop 1: Mixing Tee10:45 11:00Break11:00 11:45Domains and Boundary Conditions11:45 12:30Workshop 2: NACA Airfoil12:30 1:30Lunch1:30 2:15Workshop 3: Room Study2:15 3:00Solver Settings3:00 3:15Break3:15 4:00Workshop 4: Porous Domains4:00 4:45Post-processing4:45 5:00Rev

7、iew of DayCFX 12.0 Introductory TrainingTOC-4ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualAgenda: Day 28:30 9:00Interfaces, Sources and AVs9:00 9:30Transient Flows9:30 10:30Workshop 5: Centrifugal Pump10:30 10:45Break10:45 11:15Turbulence

8、11:15 11:45Heat Transfer11:45 12:15CFX Expression Language12:15 1:15Lunch1:15 2:00Workshop 6: Electronics Cooling2:00 2:45Moving Zones2:45 3:30Workshop 7: Tank Flushing3:30 3:45Break3:45 4:15CCL and Solver .out File4:15 4:45Overview of Advanced Physics4:45 5:00Review of DayCFX 12.0 Introductory Trai

9、ningTOC-5ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualTechnical Support ANSYS, Inc. and ASDs provide a wide range of technical support, training, and consulting services. Your Support Provider (ASD): _ Visit and select the Customer Portal

10、 link Provides access to technical support, software downloads, service packs, knowledge base TECS (Technical Enhancements and Customer Support) maintenance is required to obtain support and software updates Coming soon, search a library of example cases, tutorials, best practice guides Can also acc

11、ess support through phone / e-mail Technical Support Phone: _ Technical Support Email: _CFX 12.0 Introductory TrainingTOC-6ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualCustomer Portal Registration Visit the Customer Portal and select the

12、“Not yet a member?” link to create an accountCFX 12.0 Introductory TrainingTOC-7ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualManuals The manuals you have contain all of the material presented in the slides and the workshops The files used

13、 during the workshops are available on request The lecture appendices contain additional useful topics that will generally not be covered during the training In addition to the seven scheduled workshop, three additional workshops are provided These can be completed if time is available, or used as a

14、lternative workshopsTOC-8ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Chapter 1Introduction to CFDIntroduction to CFXCFX 12.0 Introductory TrainingTOC-9ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training

15、ManualWhat is CFD? Computational fluid dynamics (CFD) is the science of predicting fluid flow, heat and mass transfer, chemical reactions, and related phenomena by solving numerically the set of governing mathematical equations Conservation of mass, momentum, energy, species mass, etc. The results o

16、f CFD analyses are relevant in: Conceptual studies of new designs Detailed product development Troubleshooting Redesign CFD analysis complements testing and experimentation by: reducing total effort reducing cost required for experimentationCFX 12.0 Introductory TrainingTOC-10ANSYS, Inc. Proprietary

17、 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualHow Does CFD Work? ANSYS CFD solvers are based on the finite volume method The fluid region is decomposed into a finite set of control volumes General conservation (transport) equations for mass, momentum, energy, sp

18、ecies, etc. are solved on this set of control volumes Continuous partial differential equations (the governing equations) are discretized into a system of linear algebraic equations that can be solved on a computerControlVolume* FLUENT control volumes are cell-centered (i.e. they correspond directly

19、 with the mesh) while CFX control volumes are node-centeredUnsteadyAdvectionDiffusionGenerationCFX 12.0 Introductory TrainingTOC-11ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualCFD Modeling OverviewProblem Identification1.Define goals2.Ide

20、ntify domainPre-Processing3.Geometry4.Mesh5.Physics6.Solver SettingsSolve7.Compute solutionPost Processing8.Examine results9. Update ModelProblem Identification1. Define your modeling goals2. Identify the domain you will modelPreProcessing and Solver Execution3. Create a solid model to represent the

21、 domain4. Design and create the mesh (grid)5. Set up the physicsPhysical models, domain properties, boundary conditions, 6. Define solver settingsnumerical schemes, convergence controls, 7. Compute and monitor the solutionPost-Processing8. Examine the results9. Consider revisions to the modelCFX 12.

22、0 Introductory TrainingTOC-12ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training Manual1. Define Your Modeling Goals What results are you looking for (i.e. pressure drop, mass flow rate), and how will they be used? What are your modeling options? What

23、 physical models will need to be included in your analysis (i.e. turbulence, compressibility, radiation)? What simplifying assumptions do you have to make? What simplifying assumptions can you make (i.e. symmetry, periodicity)? Do you require a unique modeling capability? User-defined functions (wri

24、tten in C) in FLUENT or User FORTRAN functions in CFX What degree of accuracy is required? How quickly do you need the results? Is CFD an appropriate tool?Problem Identification1.Define goals2.Identify domainCFX 12.0 Introductory TrainingTOC-13ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights rese

25、rved.April 28, 2009Inventory #002598Training Manual2. Identify the Domain You Will Model How will you isolate a piece of the complete physical system? Where will the computational domain begin and end? Do you have boundary condition information at these boundaries? Can the boundary condition types a

26、ccommodate that information? Can you extend the domain to a point where reasonable data exists? Can it be simplified or approximated as a 2D or axisymmetric problem?Cyclone SeparatorGasRiserCycloneL-valveGasDomain of interestProblem Identification1.Define goals2.Identify domainCFX 12.0 Introductory

27、TrainingTOC-14ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training Manual3. Create a Solid Model of the Domain How will you obtain a solid model of the fluid region? Make use of existing CAD models? Create from scratch? Can you simplify the geometry? R

28、emove unnecessary features that would complicate meshing (fillets, bolts)? Make use of symmetry or periodicity? Do you need to split the model so that boundary conditions or domains can be created?Solid model of a Headlight AssemblyPre-Processing3.Geometry4.Mesh5.Physics6.Solver SettingsCFX 12.0 Int

29、roductory TrainingTOC-15ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training Manual4. Design and Create the MeshTriangleQuadrilateralPyramidPrism/WedgeTetrahedronHexahedron What degree of mesh resolution is required in each region of the domain? The me

30、sh must resolve geometric features of interest and capture gradients of concern e.g. velocity, pressure, temperature gradients Can you predict regions of high gradients? Will you use adaption to add resolution? What type of mesh is most appropriate? How complex is the geometry? Can you use a quad/he

31、x mesh or is a tri/tet or hybrid mesh suitable? Are mesh interfaces needed? Do you have sufficient computer resources? How many cells/nodes are required? Which physical models will be used?Pre-Processing3.Geometry4.Meshing5.Physics6.Solver SettingsA mesh divides a geometry into many elements. These

32、are used by the CFD solver to construct control volumesCFX 12.0 Introductory TrainingTOC-16ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualTri/Tet vs. Quad/Hex Meshes For flow-aligned geometries, quad/hex meshes can provide higher-quality so

33、lutions with fewer cells/nodes than a comparable tri/tet mesh Quad/Hex meshes show reduced false diffusion when the mesh is aligned with the flow. It does require more effort to generate a quad/hex mesh Meshing tools designed for a specific application can streamline the process of creating a quad/h

34、ex mesh for some geometries. E.g. TurboGrid, IcePak, AirPakCFX 12.0 Introductory TrainingTOC-17ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualTri/Tet vs. Quad/Hex Meshes For complex geometries, quad/hex meshes show no numerical advantage, a

35、nd you can save meshing effort by using a tri/tet mesh or hybrid mesh Quick to generate Flow is generally not aligned with the mesh Hybrid meshes typically combine tri/tet elements with other elements in selected regions For example, use wedge/prism elementsto resolve boundary layers More efficient

36、and accuratethan tri/tet aloneTetrahedral meshWedge (prism) meshCFX 12.0 Introductory TrainingTOC-18ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualMultizone (or Hybrid) Meshes A multizone or hybrid mesh uses different meshing methods in dif

37、ferent regions, e.g: Hex mesh for fan and heat sink Tet/prism mesh elsewhere Multizone meshes yield a good combination of accuracy, efficient calculation time and meshing effort. When the nodes do not match across the regions, a General Grid Interface (GGI) can be used.Model courtesy of ROI Engineer

38、ingCFX 12.0 Introductory TrainingTOC-19ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualNon-Matching Meshes Non matching meshes are useful for meshing complex geometries Mesh each part then join together Non matching mesh interfaces are also

39、used in other situations Change in reference frames Moving mesh applicationsNon-matchinginterface3D Film CoolingCoolant is injected into a duct from a plenum. The plenum is meshed with tetrahedral cells while the duct is meshed with hexahedral cellsCompressor and ScrollThe compressor and scroll are

40、joined through a General Grid Interface. This serves to connect the hex and tet meshes and also allows a change in reference frameCFX 12.0 Introductory TrainingTOC-20ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualSet Up the Physics and Solv

41、er SettingsFor complex problems solving a simplified or 2D problem will provide valuable experience with the models and solver settings for your problem in a short amount of time.Pre-Processing3.Geometry4.Mesh5.Physics6.Solver Settings For a given problem, you will need to: Define material propertie

42、s Fluid Solid Mixture Select appropriate physical models Turbulence, combustion, multiphase, etc. Prescribe operating conditions Prescribe boundary conditions at all boundary zones Provide initial values or a previous solution Set up solver controls Set up convergence monitorsCFX 12.0 Introductory T

43、rainingTOC-21ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualCompute the Solution The discretized conservation equations are solved iteratively; some number of iterations is required to reach a converged solution. Parallel processing can pro

44、vide faster solutions and access to more memory (solve larger cases) Convergence is reached when: Changes in solution variables from one iteration to the next are negligible Overall property conservation is achieved Quantities of interest (e.g. drag, pressure drop) have reach steady values The accur

45、acy of a converged solution is dependent upon: Appropriateness and accuracy of physical models Mesh resolution and independence Numerical errorsA converged and mesh-independent solution on a well-posed problem will provide useful engineering results!Solve7.Compute solutionCFX 12.0 Introductory Train

46、ingTOC-22ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualExamine the Results Examine the results to review solution and extract useful data Visualization tools can be used to answer such questions as: What is the overall flow pattern? Is the

47、re separation? Where do shocks, shear layers, etc. form? Are key flow features being resolved? Numerical Reporting Tools can be used to calculate quantitative results: Forces and Moments Average heat transfer coefficients Surface and Volume integrated quantities Flux BalancesExamine results to ensur

48、e property conservation and correct physical behavior. High residuals may be attributable to only a few cells of poor quality. Post Processing8.Examine results9. Update ModelCFX 12.0 Introductory TrainingTOC-23ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #0025

49、98Training ManualConsider Revisions to the Model Are the physical models appropriate? Is the flow turbulent? Is the flow unsteady? Are there compressibility effects? Are there 3D effects? Are the boundary conditions correct? Is the computational domain large enough? Are boundary conditions appropria

50、te? Are boundary values reasonable? Is the mesh adequate? Can the mesh be refined to improve results? Does the solution change significantly with a refined mesh, or is the solution mesh independent? Does the mesh resolution of the geometry need to be improved?Post Processing8.Examine results9. Updat

51、e ModelTOC-24ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Chapter 2Introduction to Workbenchand CFX WorkflowIntroduction to CFX CFX 12.0 Introductory TrainingTOC-25ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002

52、598Training ManualThe Workbench Environment For most situations the Workbench GUI is divided into 2 primary sections (there are other optional sections well see in a moment):The ToolboxThe Project SchematicCFX 12.0 Introductory TrainingTOC-26ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserv

53、ed.April 28, 2009Inventory #002598Training ManualThe Toolbox The toolbox contains 4 subgroups: Analysis systems: Predefined templates that can be placed in the schematic. Component systems: Various applications that can be accessed to build, or expand, analysis systems. Custom Systems: Predefined an

54、alysis systems for coupled applications (FSI, thermal-stress, etc.). Users can also create their own predefined systems. Design Exploration: Parametric management and optimization tools.CFX 12.0 Introductory TrainingTOC-27ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inv

55、entory #002598Training ManualThe Toolbox The systems and components displayed in the toolbox will depend on the installed products. Using the check boxes in the “View All / Customize” window, the items displayed in the toolbox can be toggled on or off. The toolbox customization window is normally le

56、ft closed when not in use.CFX 12.0 Introductory TrainingTOC-28ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualThe Project Schematic The Workbench project schematic is a graphical representation of the workflow defining a system or group of s

57、ystems. The workflow in the project schematic is always left to right. There are currently several applications which are native to Workbench, meaning they run entirely in the Workbench window: Project Schematic, Engineering Data and Design Exploration Non-native applications (called data-integrated

58、) run in their own window: Mechanical (formerly Simulation), Mechanical APDL (formerly ANSYS), ANSYS Fluent, ANSYS CFX, Etc . . . Blocks of cells can be deleted by RMB menu selection.CFX 12.0 Introductory TrainingTOC-29ANSYS, Inc. Proprietary 2009 ANSYS, Inc. All rights reserved.April 28, 2009Invent

59、ory #002598Training ManualThe Project Schematic In this example a Static Structural analysis type is selected for the project schematic. From the toolbox the selection can be dragged and dropped onto the schematic or simply double clicked.CFX 12.0 Introductory TrainingTOC-30ANSYS, Inc. Proprietary 2

60、009 ANSYS, Inc. All rights reserved.April 28, 2009Inventory #002598Training ManualThe Project Schematic In the example shown a structural system is dragged and dropped onto a thermal system at the Model cell (A4). Before completing the operation notice there are a number of optional “drop” locations