17.0 Release
Module 01: Core Skills Introduction to ANSYS Meshing
Overview In this lecture we will learn: •
Meshing Fundamentals
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ANSYS Meshing interface
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Geometry concepts
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Meshing methods
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Diagnostics & Usability
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Display Option
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Mesh Statistics & Mesh Metrics
Overview In this lecture we will learn: •
Meshing Fundamentals
•
ANSYS Meshing interface
•
Geometry concepts
•
Meshing methods
•
Diagnostics & Usability
•
Display Option
•
Mesh Statistics & Mesh Metrics
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Preprocessing Workflow
Meshing
Geometry Import / Creation
Geometry Cleanup / Modifications
Preprocessing and Solution
Mesh Process & Course Plan Global Controls Module 3
Meshing Methods Module 2
Core Skills Module 1
Mesh Quality Module 5
Local Controls Module 4
What is ANSYS Meshing ANSYS Meshing is a component of ANSYS Workbench •
Meshing platform
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Combines and builds on strengths of preprocessing offerings from ANSYS: – ICEM CFD, TGRID (Fluent Meshing), CFX-Mesh, Gambit
Able to adapt and create Meshes for different Physics and Solvers •
CFD: Fluent, CFX and POLYFLOW
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Mechanical: Explicit dynamics, Implicit
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Electromagnetic
Integrates directly with other WB systems
Meshing Fundamentals Purpose of the Mesh •
Equations are solved at cell/nodal locations – Domain is required to be divided into
discrete cells (meshed)
Mesh Requirements •
Efficiency & Accuracy – Refine (smaller cells) for high solution gradients and fine geometric detail. – Coarse mesh (larger cells) elsewhere.
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Quality – Solution accuracy & stability deteriorates as mesh cells deviate from ideal shape
Launching ANSYS Meshing ANSYS Meshing is launched within Workbench – 2 ways:
From Analysis Systems Fluid Flow (Fluent), Static Structural,…
From Component Systems Mesh
Double click Mesh in the System or right click and select Edit
Graphical User Interface Toolbars
Outline
Graphics window
Worksheet
Details view
Manage views
Message window
Mesh Metrics
Section Planes Entity Details Bar
Units Bar
Outline Three default sections •
Geometry – Bodies
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Coordinate Systems – Default global & user defined systems
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Mesh – Meshing operations (controls & methods)
displayed in the order in which they are inserted
In the tree •
Right clicking on any object – launches a context sensitive menu – Example: contains commands to generate, preview, clear mesh etc.
Details View Accessing Object Details •
Select an object (in the Outline) – Related information to that object are displayed in the Details View below – Ex: Select a body (“Fluid”) in the Outline •
Details of “Fluid” : contains graphical and geometric details
– To access meshing details •
•
Click the Mesh object or any of the inserted objects
The Details View provides options to – review, – edit, or – input
values for every object in the Tree
Geometry Configuration – Multiple Parts •
Geometry composed of Multiple parts – No connection between parts (no face sharing) Grid interface - Fluent
‘Contact Region’ is automatically created between 2 faces
Each part meshed independently
Results in Non-conformal interface. Meshes do not match. No nodes connection.
Independent faces
GGI - CFX Contact Mechanical
Geometry Configuration – Multi-body Parts •
Geometry composed of multiple bodies in a part – Depend on ‘Shared Topology method’ (in DM) •
None – Results in a no connection between the bodies (similar to multiple parts)
•
Automatic
Note: The CFX users will still get duplicate nodes at interface in CFX, which is fine for its solver
Faces in contact imprinted & fused to form a single face shared between 2 bodies
Results in Conformal mesh
Common face acts as ‘Interior’
Geometry Configuration – Multiple – body Parts •
Geometry composed of multiple bodies in a part •
Imprints
Faces are imprinted on each other ‘like’ faces
Contact Region is automatically created
For identical mesh on these faces, use ‘Match Control’ Results in unconnected mesh
non conformal interface
Grid interface - Fluent GGI - CFX
Meshing – 3D Geometry (1) •
3D cell Types
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First Meshing Approach
Part/Body Methods
Part/Body based •
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•
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Meshing occurs at part or body level. Meshing Methods are scoped to individual bodies. Method assignment can be automatic or manual. Bodies contained in one part are conformally meshed.
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Tetrahedrons. − Tetras only
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Sweep. − Prisms & hexahedrons
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MultiZone.
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Hex Dominant
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Automatic.
− Mainly hexahedron − Not for CFD − Sweep + PC Tet (Depends on bodies) or PC Tet
Meshing – 3D Geometry (2) •
Second Meshing Approach (mainly for CFD users)
Cut Cell Meshing
Assembly Meshing •
Meshes an entire model in one process. −
•
Assembly of parts
Performs boolean operations. Volume filling, intersection & combination − Does not require prior fluid body definition or shared topology. −
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Conformal mesh created across parts.
Assembly Meshing Methods Generate mainly
•
− −
Hexahedrons Tetrahedrons
Part/Body Meshing & Assembly Meshing not interoperable
Diagnostics: Mesh display By Body Connection (New in R17.0) Default mesh display Turning wireframe mode on
Turning on Mesh display by body connection.
Diagnostics: Close vertices (New in R17.0) ●
Close Vertices: Checks for vertices that are very close together: – Scale can be adjusted depending on model sizes
Named Selections (1) Named Selections are groups of geometric or finite element entities: •
Named selections can be created either by selecting the desired items and clicking the “Named Selection” icon in the context toolbar or RMB > Named Selection OR using the named selection worksheet (shown later).
RMB
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Named selections must be composed of “like” entities (all sur faces or all edges, all nodes, etc.).
Named Selections (2) A new criteria selection can be based on an initial selection: •
Make an initial selection followed by a RMB > “Create Named Selection”.
•
Note, initial selection must be a single entity.
Selection here will create the first row of the worksheet.
RMB >
Convert to nodal named selection immediately.
Named Selections (3) In many detail window fields Named Selections can be referenced directly:
− In the Details view, change “Scoping Method” from “Geometry Selection” to “Named Selection”
− Select the “Named Selection” from the pull -down menu
− A named selection toolbar provides quick access to basic controls “View > Toolbars > Named Selections”:
Named Selections (4) Worksheet Summary: •
•
As can be seen, numerous controls are available in the worksheet. See the documentation for a complete discussion of each. As discussed elsewhere in this course the “Convert To” action is used to change a geometry named selection (face, edge, etc.) to a nodal named selection.
When creating named selections using worksheet criteria a set of tolerances is available if needed: •
Tolerance adjustment is usually only necessary in special circumstances like models in micro units or node selections in dense meshes.
Named Selections (5)
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New in R17.0 Body Criterion Based Selection by keywords (Name) Body Criterion Based Selection by Thickness (for sheets)
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Convert to options based on connectivity
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– Find attached faces to edges based on any edge/all edges – Find attached edges to vertices based on any vertex/all vertices
Usability: Option to save mesh out to separate file (New in R17.0) ●
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When “Save Mesh Data in Separate File” is on the mesh is saved as a separate file (*.acmo). Duplication, Resume, Replace, and Save will handle the separate database and acmo files. Clear generated data will not remove the acmo file. Reset will remove the acmo file. Design Points (also w/RSM) support the separate database and acmo files.
This functionality is particularly helpful on Linux to keep file sizes smaller.
Usability: Better Meshing Status in R17.0 ● ●
Progress is reported as parts are meshed in parallel As a part is meshed the topology (edges, faces, bodies) are highlighted to show what is being worked on – This can be turned off by unchecking “Highlight” – If user stops meshing, entity will stay highlighted, allowing user to find problematic geometry easier
If user stops meshing, parts that have been meshed are done. Restarting meshing resumes only with unmeshed parts
Usability: Folders for Meshing Controls in R17.0
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Mesh controls can now be grouped for easier organization Option: Group All Similar Children, will group all objects based on type Options to suppress, rename, nest groups, ungroup, delete objects in group
Drag and drop capabilities to modify the grouping
Display Option: Color by quality
Probe Element Values
Find Min or Max value
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Displays mesh color by quality metrics
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Options to probe quality or show min/max
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Contour band can be adjusted
Display mesh contours
Section Planes (1) Displays internal elements of the mesh •
Elements on either side of plane can be displayed
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Toggle between cut or whole elements display
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Elements on the plane
Edit Section Plane button •
can be used to drag section plane to new location
Clicking on “Edit Section Plane” button will make section plane’s anchor to appear
Multiple section planes are allowed
For large meshes, it is advisable to switch to geometry mode (click on geometry in the Tree Outline), create the section plane and then go back to mesh model
Section Planes (2) ●
Shaded section planes (New in R17.0) – Shaded or hollow section plane – Plot by body color or same color for section plane
Mesh Statistics & Mesh Metrics •
Displays mesh information for Nodes and Elements
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List of quality criteria for the Mesh Metric – Different physics and different solvers have different requirements for mesh quality
Mesh metrics available in Workbench Meshing include: –
Element Quality
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Aspect Ratio
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Jacobean Ration
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Warping Factor
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Parallel Deviation
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Maximum Corner Angle
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Skewness
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Orthogonal Quality
For Multi-Body Parts, go to corresponding body in Tree Outline to get its separate mesh statistics per part/body
Mesh Metric Graph •
Displays Mesh Metrics graph for the element quality distribution
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Different element types are plotted with different color bars
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Can be accessed through menu bar using Metric Graph button
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Axis range can be adjusted using controls button (details next slide)
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Click on bars to view corresponding elements in the graphics window – Use to help locate poor quality elements
Mesh Metric Graph Controls •
Elements on Y-Axis can be plotted with two methods; – Number of Elements – Percentage of Volume/Area
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Options to change the range on either axis
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Specify which element types to include in graph – Tet4 = 4 Node Linear Tetrahedron – Hex8 = 8 Node Linear Hexahedron – Wed6 = 6 Node Linear Wedge (Prism) – Pyr5 = 5 Node Linear Pyramid – Quad4 = 4 Node Linear Quadrilateral – Tri3 = 3 Node Linear Triangle •
Te10, Hex20, Wed15, Pyr13, Quad8 & Tri6 non-linear elements
For more information about the different mesh metrics please consult module 05: Mesh Quality
Summary What have we learnt in this session: •
The global process to run ANSYS Meshing
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On overview of the interface and
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The various Geometry configurations – Multiple parts – Multi-body parts – Multiple body parts
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And the associated shared topology option
Meshing methods – Part/body based – Assembly meshing
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Section Planes
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Diagnostics & Usability
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Mesh Statistics & Mesh Metrics
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Display option
Workshop 1.1 CFD – ANSYS WB Meshing Basics
