"Previously, if we received CAD geometry, it first had to be converted into a format acceptable for Chimera Grid Tools to read, i.e., unstructured surface triangulation
or structured abutting patches. This process has always been very tedious and labor
intensive (using commercial grid generation software), and could take days or weeks.
The capability to 'read' in CAD
geometry directly into OVERGRID and then perform
surface grid generation on the CAD, was simply not available until we had the CADNexus
CAPRI CAE Gateway integration."
- Dr. William M. Chan NASA Ames
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| OVERGRID |
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NASA had a need for a robust and accurate path to import complex models directly
from major CAD systems, with minimum user intervention,
into the Chimera Grid Tools
System. CAPRI CAE Gateway was selected as a uniform gateway to major CAD systems
for the Chimera Grid Tools (CGT) software and its user base at NASA. The direct
CAD access enabled by CAPRI meant that native CAD data was available on demand for
preprocessing, which eliminated inaccuracies, bottlenecks, and additional steps
typically encountered when using CAD data in simulations. CAPRI CAE Gateway also
provides the functionality to access attributes and parameters directly from the
user's native CAD environment to enable automation of the analysis and design process.
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About OVERGRID
OVERGRID is a graphical front end for many modules in CGT. It is best suited for simulations that require creation and manipulation of overset structured grids and unstructured surface triangulations on complex configurations. CGT is commonly used in applications that utilize the OVERFLOW-2 compressible viscous flow solver, the INS3D incompressible viscous solver, and the CART3D inviscid flow solver.
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CAPRI Watertight Triangulation (Courtesy NASA) |
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As a result, CGT directly supports many important NASA projects, as well as other projects in government and industry that utilize similar grid technologies. CGT is used at NASA and over 100 organizations for CFD simulations. The software was developed at NASA Ames Research Center; Dr. William M. Chan is lead developer.
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OVERGRID User Interface
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- Preprocessing (CAD2SRF)
CAD2SRF generates a watertight triangulation representation of the CAD model with
little or no manual intervention. This triangulation can then be directly used in
OVERGRID.
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- True-to-CAD (SRF2CAD)
Takes the final mesh and snaps it back onto the native CAD model eliminating
any inaccuracies between the mesh and the native geometry. This capability also enables
mesh adaptation and mesh movement to support parametric design.
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