UG_IO SimSys FGRID 2D Grid File Type

A 2D FGRID file contains a boundary edge grid and/or a tria face planar grid. The 2D FGRID file type is derived from the FAST (PLOT3D) unstructured grid file type. 2D FGRID and FAST files are the same except for 2D FGRID boundary edge edge connectivity, boundary edge ID, boundary condition, and initial normal spacing data records described below. Also, for a 2D FGRID file the value of Number_of_Vol_Tets must be 0. The 2D FGRID file is the same as a FGRID file (for 3D) except that Number_of_Vol_Tets must be 0 and the optional boundary information records are different. In addition, the Z coordinate values should all be set to the same value.

     { Number_of_Nodes, Number_of_Trias, Number_of_Vol_Tets }

     { [ X for node 1, X for node 2, ... X for node Number_of_Nodes ],
       [ Y for node 1, Y for node 2, ... Y for node Number_of_Nodes ],
       [ Z for node 1, Z for node 2, ... Z for node Number_of_Nodes ] }

     The Z coordinate value is ignored.

     { [ ( index for node 1 of face 1,
           index for node 2 of face 1,
           index for node 3 of face 1 ),
         ( index for node 1 of face 2,
           index for node 2 of face 2,
           index for node 3 of face 2 ),
         ...
         ( index for node 1 of face Number_of_Trias,
           index for node 2 of face Number_of_Trias,
           index for node 3 of face Number_of_Trias ) ]

       [ dummy ID for face 1,
         dummy ID for face 2,
         ...
         dummy ID for face Number_of_Trias ] }

     { Number_of_Bnd_Edges }

     { ( index for node 1 of boundary edge 1,
         index for node 2 of boundary edge 1,
         edge ID for boundary edge 1 ),
       ( index for node 1 of boundary edge 2,
         index for node 2 of boundary edge 2,
         edge ID for boundary edge 2 ),
       ...
       ( index for node 1 of boundary edge Number_of_Bnd_Edges,
         index for node 2 of boundary edge Number_of_Bnd_Edges,
         edge ID for boundary edge Number_of_Bnd_Edges ) }

     *{ [ grid boundary condition flag for boundary edge 1,
          grid boundary condition flag for boundary edge 2,
          ...
          grid boundary condition flag for boundary edge Number_of_Bnd_Edges ] }*

     *{ [ initial normal spacing for node 1,
          initial normal spacing for node 2,
          ...
          initial normal spacing for node Number_of_Nodes ] }*

     Number_of_Bnd_Edges	: Number of boundary edges.
     Number_of_Trias	: Number of triangular faces.
     Number_of_Vol_Tets	: Number of tetrahedral volume elements that must be set
    			  equal to 0.
     Number_of_Nodes	: Number of grid nodes.

For a 2D planar grid the Number_of_Vol_Tets must be zero. In the above description, the parentheses ( ... ) are for grouping, the brackets [ ... ] enclose items in a loop, and braces { ... } enclose items in a single logical record. The items in starred braces *{ ... }* are optional records for grid files that describe a boundary edge grid. If Number_of_Trias is greater than zero (the grid is a 2D planar grid and not a 2D boundary edge grid) then this data is not read in or written out. The optional records can be included in whole or in part as long as they are in the correct order. The UG_IO grid file reader will attempt to read the "grid boundary condition". If it is not found then reading of the file will end. Finally, the reader will attempt to read the "initial normal spacing".

In FORTRAN unformatted form, the data must be written out or read in using the specified record format. The floating point data items must all be either real*4 or real*8 data. In C binary form, the data may be written out or read in using records the length of loops or of the individual data items. The floating point data items must all be either float or double data. In ASCII formatted form, the data may be written out or read in using records the length of loops or of the individual data items. Data items may be written out in free format of any specific form.

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