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Table of Contents
Software Execution
GUI Design & Operation
CAD & Geometry
Element Sizing
VGRID Sources
FELISA Sources
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GridEx Tutorials
Geometric Primitives & Solid Operations
Generic Wing/Body - FELISA Sourcing
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Feature Suppression & Regeneration
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Transformations & Displacement

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Software Execution

  This section describes the data the user must supply to successfully execute GridEx. The valid data formats and their associated geometry kernels are explained in detail below.

Required Data

  GridEx operates upon geometry in the form of a solid model which defines the computational boundary for the body of interest.  It is generally assumed that this model has been developed using a third party CAD package using the full capability afforded therein to efficiently produce a manifold or "water tight" solid model of the geometry.  Such models may be available from earlier phases of the design process.  Additionally, the ability to create geometric primitives, utilizing the original CAD system kernel, is available within GridEx.  Boolean combinations of geometry are provided thereby allowing the user to define the computational domain of interest.

 Through the use of CAPrI, a third-party CAD-vendor neutral Application Programming Interface (API) from MIT, GridEx is able to support the use of the following popular CAD packages:

  • CATIA, by Dassault Systems.
With CAPRI, GridEx can efficiently "communicate" directly with the appropriate geometry kernel thus ensuring that all meshing and geometry operations performed within the software are fully and seamlessly linked to the underlying geometry as all such operations make use of the native definitions contained within the model file. GridEx is thus essentially immune to modeling issues which typically arise due a translation of native CAD data into IGES or STEP formats.  This functionality, however, requires an active license of the respective CAD package as its geometry kernel is accessed directly by the software.  It also requires that the input geometry be in the form of a proper manifold as defined by the native CAD geometry kernel (i.e., a valid solid).

  Though it is not the preferred mode of operation, GridEx will also accept a solid model description in a native format to accommodate situations in which the GridTool software has been used to develop the model.  In any event, the model must be complete and possess no geometric faults which violate the manifold requirement as GridEx offers no facilities with which to repair such deficiencies or modify configuration geometry.  With a valid solid model, the user is ready to begin processing within GridEx.

Software Execution

  GridEx execution requires, at a minimum, the command line identification of the solid modeling kernel.  The command has the form:

        GridEx  kernel
where kernel may be specified as either:
  • Ideas,
  • Parasolid,
  • Pro-E,
  • Catia, or
  • Native
and is case insensitive.  Specification of other than the Native "kernel" will instruct GridEx to link the designated geometry kernel. Specific model file name extensions are dictated by the respective modeling kernel and are required as listed in the table below:
Model file
Default extension

 The Native option is provided for situations as described above where legacy GridTool data is available. No external geometry kernel is linked for this selection.

  The command described above can optionally be appended with options if it is desired that the model file be read from the command line. The valid options consist of the following:

  • -capri,
  • -fbg,
  • -vbg,
  • -P, or
  • -M
  • The capri option instructs GridEx to read the designated model file (having the extension required by the respective kernel), thus the command becomes
          GridEx  kernel -capri modelfile.extension
    However, if a CAPrI ancillary data file (modelfile.capri) exists, it will be loaded first and subsequently trigger the loading of the model file. This ancillary file exists if the model has been previously processed within GridEx or CAPrI and output as CAPrI geometry.  This ancillary file supplements the kernel model file with additional data (including Boundaries, Tags, etc.) but contains no actual geometry definition.

    The fbg option indicates a FELISA background mesh file (modelfile.bac) containing information relating to the definition of the background grid with all associated sources.

    The vbg option indicates a VGRID background mesh to be read from a traditional VGRID D3M file (modelfile.d3m). Only the background grid sources are read from the D3M file. All other information (curves, patches, etc.) is discarded.

    The P option indicates an I-DEAS project file [Project].

    The M option indicates an I-DEAS model file [ModelFile].

    Alternatively, the importing of model data can be performed using the File Dialog facilities provided within the software.

    Responsible NASA Official: William T. Jones
    Site Curator: William T. Jones
    Comments and Questions
    Last Updated: Dec 12, 2001