multizone meshing for a tank geometry with piping
TRANSCRIPT
7-1ANSYS, Inc. Proprietary© 2009 ANSYS, Inc. All rights reserved.
April 28, 2009Inventory #002645
Multizone Meshing for aTank Geometry with Piping
Workshop 7.2
Introduction to MultiZone Meshing
7-2ANSYS, Inc. Proprietary© 2009 ANSYS, Inc. All rights reserved.
April 28, 2009Inventory #002645
Training ManualGoals
• This tutorial will show how to use the Meshing Application in ANSYS 12 to generate a mesh suitable for a CFD simulation of a chemical process flow.
• The geometry, consists of three bodies representing a tank together with a single inlet and outlet pipe.
• The goal is to produce an Hex mesh throughout the domain without any further decompositionof the geometry using the Multizone Method.
Introduction to MultiZone Meshing
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April 28, 2009Inventory #002645
Training ManualCreating a Standalone Meshing System
1. Launch ANSYS 12.0 Workbench from the START menu
2. Open the Component Systems section of the Toolbox on the LHS of the WB GUI.
3. Double click the Mesh option
Introduction to MultiZone Meshing
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Training ManualImporting the Geometry
4. Right click on the Geometry button in the RHS of the WB panel and select Import geometry (the question mark on the button turns to a tick once a geometry file is imported)
5. Import the 2-pipe-tank.agdb file
6. Double click on the Mesh button to launch the Meshing Application
Introduction to MultiZone Meshing
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Training ManualGeomety
7. The original geometry was modified in DesignModeler
• The tank was split into three bodies and some simplification was made to remove small faces that are not important to the analysis
• One multi-body “Part” was created and a given the name “Fluid” and the material type “Fluid”
• Individual bodies were re-named
Introduction to MultiZone Meshing
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Training Manual
8. In the Meshing Options panel to the RHS of the main window select the
following meshing options:
– Physics Preference
• CFD
– Mesh Method
• Automatic
– Click OK after you
made the selections
– In Units, make sure
it is set to Metric, mm
*Note: If you are using ANSYS V14.0
or more recent versions of ANSYS then
you will not see the Meshing Options panel
at the start of ANSYS Meshing. You will
still be able to set the Physics Preference
and insert any Mesh Methods manually or set
your defaults from Tools>Options..>Meshing
Meshing Options
Introduction to MultiZone Meshing
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Training ManualNamed Selections
9. Named Selections are used to assign Fluent name and zone types
• Set the Cursor Mode to Face selection
• Select the inlet face
• RMB select Create Named Selection
• Assign the name Inlet
• Repeat for Outlet
• A naming convention has
been established to
automatically assign zone types in Fluent
• For example -
– “Inlet”
• Velocity-inlet zone
– “Outlet”
• Pressure-outlet zone
See Fluent Mesh export section
of the manual for all options.
Introduction to MultiZone Meshing
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Training ManualGlobal Mesh Settings
10. Set Global Size and Quality control
• Click on Mesh in the Model Tree to open up the Details of “Mesh” panel
• Sizing
– Turn Off Use Advanced Size Function• Multizone does not use this option
– Change the Relevance Center
• Fine
• Recommended for most CFD applications that apply the Multizone Method
• Statistics
– Assign Mesh Metric
• Option Skewness
• Maintain all other defaults
Introduction to MultiZone Meshing
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Training ManualInserting a Multizone Method
11. Insert Mutizone Meshing control
• Set the Cursor Mode to Body selection
• RMB (in Window) – Select All the bodies
• RMB (in Tree) – Insert – Method
• Select Multizone
Introduction to MultiZone Meshing
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Training ManualSetting Multizone Sources
12. Select Mutizone Source faces
• Change Src/Trg Selection – Manual Source
– To ensure the middle section can be swept
• Set the Cursor Mode to Face
• Pick the five green source faces(see top image)
• Rotate the model to look at therear of the tank
• Pick the additional fivered source faces(see bottom image)
• Apply
Introduction to MultiZone Meshing
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Training ManualGenerating the Initial Mesh
13. Create an initial Mesh of the model
• RMB (in Tree) – Generate Mesh
• The mesh is successfully created – but refinement is clearly needed
– The mesh at the inlet and outlet pipes and close to the pipe/tank intersection is insufficient to capture the physics correctly
– This can be achieved by inserting some additional meshing instructions such as Inflation, Sizing and Biased Sizing to improve the pipe/tank meshing
Introduction to MultiZone Meshing
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Training ManualFace Sizing
14. Add Face Sizing for the pipes to control the size of elements
• Start by removing the mesh
– RMB (in Tree) – Clean and confirm
• Make sure you’re using Face Selection and pick the four faces shown in Green
• RMB (in Tree) – Insert – Sizing
• Set Sizing Details: Set Element Size
– 1 mm
Introduction to MultiZone Meshing
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Training ManualAdding Inflation
15. Add Inflation(boundary layers)
• Set the Cursor Modeto Body Selection
• Select the centralgreen body
• RMB (in Tree) – Insert – Inflation
16. Set Inflation Details
• Switch to Face selection
• Select the four green cylindrical faces and Apply
• Set Inflation Control
– Number of Layers• 2
– Maximum thickness• 1 mm
Introduction to MultiZone Meshing
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Training ManualEdge Sizing
17. Add Edge Sizing
• Change Cursor Modeto Edge Selection
• Select two green edges on one side
• Rotate the model
• Repeat the selection
• RMB (in Tree) – Insert – Sizing
18. Set Sizing Details
• Element Size
– 1mm
• Behaviour
– Hard
• Bias type
– _ __ ___ __ _
• Bias Factor
– 6
Introduction to MultiZone Meshing
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Training ManualGenerating the Final Mesh
19. Generate the mesh
• RMB (in Tree) – Generate Mesh
• Statistics
– Elements
• ~45,000
– Max Skewness
• Below 0.8
• Overall a good Quality mesh
Introduction to MultiZone Meshing
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Training ManualExamining the Mesh
20. Examine the Mesh
Inflation –
on the pipe
walls
Sizing – 4
elements
on face
Sizing – element size 1mm
across pipe and biasing to
increase density at transition
Introduction to MultiZone Meshing
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Training ManualSaving the Project
21.The mesh is now complete
• RMB (Tree) select Update
• Select File > Close Mesh to close the Mesh application
• In the WB panel select File > Save Project As… and give the project a name
• Exit from ANSYS Workbench by selecting File > Exit
22.Further Work
• Change the mesh settings for each of the additional parameters
– How do each of these parameters influence the mesh?