Pre-Processing Utilities get Your Grid Ready for Use with the Wind-US CFD Analysis Software

The Wind-US code is just one part of a fairly complete CFD analysis software package. In addition to the core Navier-Stokes solver, there are a variety of tools to make it easier for users to set up cases and analyze the results.


The NPARC Alliance does not provide grid generation utilities, per se, so users must accomplish this task using some other package (e.g. Gridgen, CFD-GEOM, or ICEM, to name just a few). Many of these packages can export grids directly to the “Common File Format” that the Wind-US CFD analysis software uses. With others, it will be necessary to use a file conversion utility (more about that later).

Once you have your mesh, there are two major utilities available for inspecting the mesh and setting boundary conditions: GMAN and MADCAP. Note that some grid generators allow you to specify boundary condition types as you generate the mesh; in that case, a separate utility might not be necessary.


GMAN is the original interactive menu-driven pre-processor that is used to specify boundary condition types, and zone connectivity in multi-zone grids. It also provides important quality checking, display, and reporting functions. GMAN is primarily used for structured grids, although it can also work with single-block unstructured meshes.

Screenshot of the GMAN pre-processor in action

GMAN has two user interface modes; a command line mode, and a graphical menu-driven mode. In the command line mode, the user types commands in a text window or runs a script file containing the commands to be performed. The commands are processed as they are entered.

In the menu-driven mode, the user operates in a graphical environment, and controls operations and display functions using menu picks. This mode provides interactive display of a computational grid, which greatly enhances boundary condition specification by allowing the user to see the boundaries being specified.

The user can switch between command line and graphic menu modes at any time. All operations except display control are saved to a journal file in a readable format which can be easily edited and played back to repeat a set of operations.


MADCAP (Modular Aerodynamic Design Computational Analysis Process) is a tool developed in the Applied CFD group at Boeing Phantom Works in St. Louis as a successor to GMAN and several other utilities. The Boeing version of MADCAP is linked with the AFLR3D mesh generation package, but the public version distributed by NPARC has no grid generation capabilities.

While MADCAP's user interface and code infrastructure are new, the underlying routines for structured grids are largely from GMAN. On top of this, a significant amount of new technology has been added to support unstructured grids.

The NPARC version of MADCAP got off to a bit of a rocky start, with many people struggling just to get the software to run at all on their systems. More recent versions have largely addressed these issues, and the software is proving itself useful as the unstructured solver in Wind-US becomes more capable.

In fact, MADCAP is required to set boundary conditions and inter-block connectivity for multi-block unstructured grids (or grids which combine structured and unstructured meshes), as GMAN cannot read such files. MADCAP is also required if you wish to import an unstructured grid file that is a format other than the Common File Format. The UG_IO library from the SimCenter at Mississippi State University is used for file import and export.

But Wait, There's More...

With GMAN and MADCAP, you can get a grid ready for Wind-US CFD analysis software to use, but once you get a solution, you also need to analyze the results. The next part of this review discusses post-processing options.

If you have specific questions, feel free to contact me about the Wind-US utilities and I'll be happy to try to answer them.

Alternatively, you can return to the discussion of parallel processing options in the Wind-US code, or return to the introduction page of this review of the Wind-US CFD analysis software If you've had all you can take of the Wind-US code, you can check out the review of another CFD analysis software package or return to the Innovative CFD home page and browse one of the other topics.

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