ICEM CFD hybrid meshing tutorial presentation

ICEMCFD_hybrid_meshing

1. ICEM CFD 5.1 New Features
Workshop 15
Hybrid meshing of a simple
HVAC assembly

2. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-2
© 2004 ANSYS, Inc.
Create a Project
Choose “Open Project“ Icon
Browse to the desired working directory
Enter the project name
Type in the File nameas: HVAC_Hybrid.prj
Tips:
The pull down next to the file name can be used
to quickly locate recently used projects.
In Windows, The File browser is a standard
Windows file browser offering all the
functionality of windows explorer.
In Unix or Linux, similar functionality is also
available.
The Project filecontains information about project settings, the working folder and file associations.
Once the geometry, mesh, boundary conditions, parameter files etc. are saved with the project file,
simply loading the project file will also load these associated files.

3. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-3
© 2004 ANSYS, Inc.
Open Geometry
Open The Geometry:
File -> Geometry -> Open Geometry Or use the
“Open Geometry” ICON
Select: Hybrid_HVAC.tinusing File Browser
Display: activate Surfacesby left mouse click on icon
Display: Solid & Wire mode thru right mouse click on
Surfaces in Display Tree
Display: Transparent mode thru right mouse click on
Surfaces in Display Tree
Display Tree
HVAC

4. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-4
© 2004 ANSYS, Inc.
Managing the Model tree will be very important for this tutorial. For
your convenience, the two primary halves of the model, the
Hex_Partand the Tetra_Part, have been placed in separate
assemblies.
The surface between the Hexa and Tetra volumes has been placed
in the Interfacepart
To turn a part or assembly on or off, click on the glasses ICON.
We will start by turning the Tetra assembly OFF
Manage Parts
Hexa
Interface
Tetra

5. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-5
© 2004 ANSYS, Inc.
Turn off the Tetra Assembly so only the Hexa Assembly and
interface Surface are active. Its time to Hex Mesh this half
of the assembly.
Hex meshing is not the focus of this tutorial, so we can skip the
details of this step and load the blocking file I have provided
Load Blocking:
–File => Blocking => Open Blocking Or use the Open
Blocking utility icon
–Open: HVACPipeBlocking.blk
Generate Mesh:
–Expand the Blockingbranch of the model tree
–Activate thePre-mesh andRecompute
–RMB on Pre-meshand select Convert to Unstruct
Mesh
–Save the project
#1
Hexa Meshing
Compute
Pre-Mesh

6. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-6
© 2004 ANSYS, Inc.
Many curves
are filtered out
Only essential
feature curves
remain
Build Topology
BUILD TOPOLOGY:
–Geometry -> Repair Geometry -> Build Diagnostic Topology
–Default:Tolerance is auto-calculated as0.1
–Filter by angle: Turn on Filter points and Filter curves
–Default:New Part Nameis set toInherited
–Turn on:Only active parts
•This will prevent build topology from filtering out the curves on the Hex_Part
–Accept other defaults and press Apply
#1 #2
#3
#5
#7
#4
#6
Now lets switch to the tetra portion. Turn off the Hex_Partassembly and turn on the
Tetra_Partassembly.

7. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-7
© 2004 ANSYS, Inc.
Assign Element Size:
–Mesh -> Set Surface Mesh Params
–Select all the surfaces with the “a” hotkey.
–Set: Maximum element size to 4.
–Defaults: other settings should remain 0.
–press Apply.
Display Element Sizes:
–RMB on surfaces
–Select Tetra Sizes from
the pull-down
#1
#2
#5
#4
#3
Set Mesh Sizes
Control
Display
through
RMB
Tetra icons indicate
tetra mesh sizes set
on each surface

8. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-8
© 2004 ANSYS, Inc.
Display:
–Expand the Geometry
Branch and activate all the
sub branches.
–Make sure the Fluid and
Interface part, as well as
the Tetra_Part assembly
are active.
–Make sure the Hex_Part
assembly is inactive
Save Project:
–We will not be able to tetra
mesh in batch mode
without first saving the
project
#1
Control Display
This next part is very important. We are going to mesh only the visible
tetra_partof this HVAC assembly. We need to make sure that all
the correct components are visible.

9. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-9
© 2004 ANSYS, Inc.
#1
#2
Mesh Tetrahedral
Mesh Tetrahedral:
–Mesh -> Mesh Tet -> From geometry
–Activate: “Smooth transition”
–Activate: “Run as batch process”
–Activate: “Only visible geometry”
–press Apply.
#3
#4
#6
#5
#7

10. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-10
© 2004 ANSYS, Inc.
#1
#2
Load Hex Mesh with Tetra Mesh
Load Hex Mesh:
–File -> Mesh -> Open Mesh or
use Open Mesh icon
–A mesh is already loaded, how
do you wish to proceed
•Merge
–Display all the shells and both
part assemblies
#3
This Merge simply
concatenates the
mesh files, the
nodes are not
connected

11. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-11
© 2004 ANSYS, Inc.
Inspect Interface shells
View the interface area:
–Expand the mesh branch and the shells branch
–Activate the shells branch
–Turn off all the parts except interface
–Turn off the geometry
–Alternately display and blank the triangles and quads to see
that both layers are at the interface and are non conformal
Triangles
Overlapping
Triangles and
quads
Quads

12. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-12
© 2004 ANSYS, Inc.
Inspect interface volume
Display Mesh Cut Plane:
–RMB on Mesh,
selectCut Plane
–The Define Cut
Planes window
appears
–Change Method to
Middle-X
–Adjust Fraction value
to 0.65
–Display Mesh Volumes in the
model tree
–Zooming in reveals that the
mesh needs to be merged

13. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-13
© 2004 ANSYS, Inc.
Merge mesh:
–Edit Mesh => Repair Mesh => Merge
Meshes
–Method: Merge volume meshes
–Merge surface mesh partsand select the
INTERFACEPart.
–Accept and Apply
Observe:
Using the cut plane, observe that the mesh is
now node for node conformal across the
interface.
#2
#1
#4
#3
#5
Merge Mesh
#7
#6

14. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-14
© 2004 ANSYS, Inc.
The interface quads still remain
Delete the Interface shell mesh:
–Edit Mesh => Delete Elements
–Use the Select mesh elements tool bar to select
items by part
–select the INTERFACEpart.
–Accept
The interface surface mesh is removed opening up the
part for flow.
Save the Project
#2
#1
#4
#3
#5
Delete shells

15. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-15
© 2004 ANSYS, Inc.
Add Prism Layers:
–Mesh => Mesh Prism
–Name the New volume part “Prism”
•Normally, leave this blank and the prisms
will inherit their volume part from the
original volume
–Select parts to mesh
•From the popup, select all the parts
except the inlet, outlets and interface
•Leave the other fields blank
•Accept
–Set: Initial height to 0.6
–Default: Height ratio of 1.2
–Set: Number of layers to 2
–Compute Paramsto calculate total height
–Accept the other defaults
–Apply
–Load the Prism Mesh!
#2
#1
#4
#3
#5
Mesh Prism
#6
#7
#8

16. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-16
© 2004 ANSYS, Inc.
Display:
–Using the Mesh Cut Plane and transparent surfaces, view the mesh
•The Prism portion is currently an orange color, while the tetra and Hexa
are blue and dark blue respectively. On the outer surface, the shells (tri
or quad) take on the color of their respective surfaces
•The Volume element types now list Prisms
–More/thicker layers are possible, but limited
by the height of the first volumetric hexa
•Prism layers can also be split
and redistributed from the
Edit Meshmenu
Display Hybrid Mesh

17. ICEM CFD 5.1 New Features
Workshop
ANSYS ICEM CFD v5.1
October 1, 2004
Inventory #002157
WS15-17
© 2004 ANSYS, Inc.
Observe:
–In the interface region, the prisms are
uninterrupted
Next Steps:
–The elements may all need to be in one
volume, use the model tree to add all three
volume regions into one volume part.
–Smoothing/Diagnostics/Repair
–Use the Output tab to select a solver
–Apply Parameters and boundary conditions if
desired
–Export to solver
Next steps
Hexas
Tetras
Prisms
Quads Tris
Pyramids