Graphical representation of results from mathematical models, such as numerical simulations of two-dimensional hydrodynamics problems, is of great importance to provide an accurate interpretation and a global vision of the results. These results must also be post processed in order to compare results or to use them for design specifications. CAD packages provide a powerful mean for such graphical and numerical postprocessing. A set of FORTRAN subroutines to obtain isolines from an array of nodal values in a numerical grid has been developed. The order of the interpolation scheme is quasi-bicubic. Actual processing is carried out in two steps, by performing bilinear interpolation first, then smoothing by local averaging of the gradient. Continuity of the function and its gradient on the edges of adjacent cells is obtained. Output from the program is given in the form of a DXF database file, which contains specifications of all attributes for a complete representation of a polyarc graphic entity for each isoline branch. One or more DXF files can then be imported by AutoCAD for advanced post-processing.
