ASCII2D format

``ASCII2D'' is a simple data format for small 2D problems. Each line of the data file is coded in ascii and can be easily edited, or produced by programs, or both.

A line begining with the characters #, /#, %%, %! is a comment line. Other lines are composed of tokens. Each token is a character string, and tokens are seperated by one or more of the characters ``space'', ``tabular'' or ``new line''. Each token is a keyword or data associated to a keyword. The available keywords are:

• nblocks

  This keyword is optional, if omitted the number of blocks is one. If not this keyword must be followed by an integer value specifying the number of block of a 2D unstructured mesh.

• points

  This keyword must be followed by an integer value specifying the number of nodes of a 2D unstructured mesh and by two decimal values for each nodes specifying its coordinates.

In the case of homogeneous meshes.

• triangles

  This keyword must be followed by an integer value specifying the number of triangles of the 2D mesh to define and by three integer values for each triangles specifying the node index of the vertices. The node index of the first point has the value 0.

• quadrangles

  This keyword must be followed by an integer value specifying the number of quadrangles of the 2D mesh to define and by four integer values for each quadrangle specifying the node index of the vertices. The node index of the first point has the value 0.

In the case of non-homogeneous meshes.

• polygons

  This keyword must be followed by an integer value specifying the number of polygons of the 2D mesh to define. Then the lines following define the number of the vertices and integer values for each polygon specifying the node index of the vertices. The node index of the first point has the value 0.

• scalars

  This keyword must be followed by the name of the value and by as many values as there are nodes in the mesh.

• vectors

  This keyword must be followed by three strings specifying the names of a vector variable and the name of two scalar variables what will be the componants of the vector variable. These strings must be followed by a decimal value what will be used as a coefficient multiplicator for the computation of each step of the stream lines following the field vectors. After this coefficient two decimal values for each node are the componants of the vector knwown at the node position.

• end_block

  This keyword must follow each block. It can be omitted after the last block if there are not function definitions in the ``ascii2d'' file..

The last block can be followed by some keywords defining the creation of new scalar values from the previously defined by predefined functions. Theses keywords and the associated functions can also be used in the description file and are described in the section ``Description file''.

An example is available with the sample data, in the file ``soupap.ascii2d''

Two other short examples follow (each in one column):

%%non-homogeneous mesh           %%homogeneous mesh
# with scalars                   %! with vectors and scalar
# mesh points
points 9                         points 9 
-4  8.                                 -4  8. 
 8. 8.                                  8. 8.
-8  4                                  -8  4  
 0  4                                   0  4 
-8  0                                  -8  0
-4  0                                  -4  0
 4  0                                   4  0
 8 -4                                   8 -4
-4 -8                                  -4 -8
polygons 9                       triangles 9
4 2 3 0 1                              2 3 0
3 3 6 1                                3 6 1
3 2 5 3                                2 5 3 
4 4 5 2 0                              4 5 2                      
3 5 8 3                                5 8 3
5 3 8 6 0 2                            3 8 6
4 6 7 1 2                              6 7 1 
3 4 8 5                                4 8 5
3 8 7 6                                8 7 6 
scalars rho                      vectors champ1 champ1.u champ1.v .1
1                                      1 3
4                                      1 4
6                                      1 6
5.3                                    2 5.3
2                                      2 2
3                                      2 3
2                                      2 1
0                                      0 2
5                                      5 1
                                  end_block
                                  veclen: l_champ1 champ1