Home  CFD-GEOM User Tips Surface Trimming Utilities and Shortcuts in CFD-GEOM
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Surface Trimming Utilities and Shortcuts in CFD-GEOM |
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CFD-GEOM provides several
surface and trimming loop creation tools. Surface creation and trimming
can be greatly simplified, depending upon what you want to do with the
surfaces. In most of the cases, surfaces are used to generate
unstructured triangular and quad meshes on trimmed surfaces.
Surfaces can also be used to create new geometric entities, such as
curves. In some
cases, users may project (i.e. map) structured faces to trimmed or
untrimmed surfaces. Some of the tools outlined in this tip would
allow
users to avoid two or three manual steps like surface and loop creation.
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Trim
Surfaces from Curves:
The Trim Surface from Curves tool is a new tool in
CFD-GEOM V2004 that enables you to generate a trimmed surface using any
number of curves or edges that form a closed circuit. As shown in
Fig 1, on a set of lines, curves, or edges (it could be planar or
non-planar),
you can use this tool to create trimmed surfaces directly without
manually creating the surfaces, loops and trimming loops. Fig 2.
shows
the trimmed surface created from non-planar set of curves.
Summary:
Input : Lines, Curves, or Edges
Output: Surface, Trimming Loop, Trimmed Surface
Comments: Can work on planar or non-planar curve sets.
Trimmed Surfaces from Planar
Loop:
This tool automatically covers each selected loop with a
NURBS surface
and then trims each surface with the appropriate loop. The selected
loops may lie in arbitrary planes. However, all loop entities must lie
in the same plane. Fig 3 shows an
interpolated curve on a set of points. Fig 4 shows the loop on the
interpolated curve. Once the loop is created, within one click, the
trimmed surface can be created as shown in Fig5.
This tool can
be used on complex
2D or 3D geometries where surface creation on closed curves can be
difficult, time consuming, or impossible.
Summary:
Inputs: Trimming Loop
Output: Surface, Trimmed Surface
Comments: Loop must be planar, but can have any orientation
2D Domain from Loops:
This tool allows the user to
create 2D domains directly from a loop. In CFD-GEOM V2003, this
tool was located in Tools -> Utilities, but has been moved to Grid
-> Surface Set and Domain Options in V2004. The loop entities
must
lie on the X-Y plane (any constant Z-plane) of the model. Fig 6
shows a loop on a set of
closed curves. 2D
domain from loops will allow the user to create a 2D unstructured
domain
as shown in Fig 7. 2D triangulated or quad grid can be put on the
unstructured domain as shown in Fig 8 and finally 3D prismatic domain
can be created through extrusion or revolution as shown in Fig 9.
Summary:
Input: Trimming Loop
Output: Surface, Trimmed Surface, Open Surface Set, 2D
Unstructured Domain
Comments: Loop must be on the X-Y plane or constant Z-plane
If you have any questions about
this feature or would like us to discuss some other topic in the
future, please let us know.
Amit Saxena
Customer Support Engineer
ESI Group
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Using Radial Extrusion in CFD-GEOM
The Radial Extrusion tool allows you to extrude
structured faces and unstructured surface grids about
a specified axis. Extrusion is performed radially
about a user-specified axis, typically the center
line of the collection of entities being extruded. A
variety of options exist for specifying the reference
axis and for controlling certain aspects of the
extrusion.
Repairing Imported CAD Geometries in CFD-GEOM
In most cases, importing CAD files in CFD-GEOM results in a clean
geometry that can be directly used for further processing and/or
meshing. However, for complex models, it is possible that the imported
geometry has missing, untrimmed or defective surfaces that need to be
manually repaired.
New Exposed Boundaries Visualization tool in CFD-GEOM
One of the various new features introduced in CFD-GEOM V2009.2 is the ‘Exposed Boundaries’
visualization tool. This tool allows users to quickly visualize those areas where closure
problems remain in an otherwise closed and “watertight” model.
Advanced Blanking and Picking Tools in CFD-GEOM Manipulating very large, complex
models can be a challenging task, especially
when small features of the geometry are included. CFD-GEOM has
many
advanced blanking/unblanking tools, as well as advanced picking tools,
that can make dealing with large models easier.
Using Interior Sources for Mesh Control in CFD-GEOM
The key ingredient in ensuring good behavior of the
mesh during grid generation is the inclusion of
adequate mesh control. One way to
accomplish mesh control in CFD-GEOM is by using
Interior Sources when you are using an unstructured
mesh.
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