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CGNSBASE - Use CGNS files

CGNSBASE basename

This keyword specifies that the grid and flow data are obtained from, and written to, CGNS (CFD General Notation System) files, not common files. The user-specified basename is the name of the CGNSBase_t node in the grid and flow files. [Detailed information on the CGNS standard may be found at the CGNS web site external link.]

It should be noted that, strictly speaking, there is no notion of a CGNS file, only of a CGNS database implemented within one or more ADF (Advanced Data Format) files. We nevertheless use the terminology "CGNS file" in the Wind-US documentation. In addition, a true CGNS database has a single CGNSBase_t node as its root. In the current Wind-US implementation, however, the grid and flow solution are stored in separate files, with both files having their own CGNSBase_t node with the same basename.

When CGNS files are used, the extensions for the grid and flow files must be .cgd and .cfl, respectively, the same as when common files are used. If the CGNSBASE keyword is used, the files are read as CGNS files. If the CGNSBASE keyword is not used, they are assumed to be common files.

Wind-US supports the most common CGNS features, but not all. Some specific limitations on the implementation of CGNS in Wind-US are listed below.

There are also some Wind-US features and capabilities that are not supported by the current CGNS standard. These include chemistry and MFD flows, specified boundary layer transition, and bleed boundary conditions. Several proposals are pending to extend the CGNS standard, but for now CGNS files created by Wind-US for these types of flows may not be fully CGNS compliant, and should be considered unique to the Wind-US implementation.


Last updated 17 Feb 2005