FEM_TO_MESH
Convert finite element mesh data from FEM to MESH format

FEM_TO_MESH is a FORTRAN90 program which reads a pair of FEM files defining the node coordinates and elements of a finite element mesh, and rewrites the data as a MESH file.

The program can convert 2D meshes of triangles, or 3D meshes of tetrahedrons.

Usage:

fem_to_mesh prefix

• prefix_nodes.txt is a file containing node coordinates;
• prefix_elements.txt is a file listing the nodes forming each element;
• prefix_boundary_node_mask.txt is a file listing a "0" for each interior node and a "1" for each boundary node; (This file can be created by the triangulation_boundary_nodes or tet_mesh_boundary programs.)
• prefix.mesh is the name of the MESH file to be created.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

FEM_TO_MESH is available in a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

FEM_TO_TEC, a FORTRAN90 program which converts FEM models into TECPLOT ASCII files.

FEM2D, a data directory which contains examples of 2D FEM files, text files that describe a 2D finite element geometry and associated nodal values;

FEM3D, a data directory which contains examples of 3D FEM files, three text files that describe a 3D finite element geometry and associated nodal values.

ICE_TO_MESH, a FORTRAN90 program which reads a NETCDF file containing an ICE dataset and rewrites the information as a MESH file.

MESH, a data directory which contains examples of MESH files, which can be used to define the geometry of a finite element mesh in 2D or 3D, using triangles, quadrilaterals, tetrahedrons or hexahedrons.

TET_MESH_BOUNDARY, a FORTRAN90 program which returns the nodes and faces of the boundary of a tetrahedral mesh, which themselves form a 3D triangular mesh or "TRI_SURFACE".

TRIANGULATION_BOUNDARY_NODES, a FORTRAN90 program which reads data defining a triangulation, determines which nodes lie on the boundary, and writes their coordinates to a file.

Reference:

1. Pascal Frey,
   MEDIT: An interactive mesh visualization software,
   Technical Report RT-0253,
   Institut National de Recherche en Informatique et en Automatique,
   03 December 2001.

Source Code:

• fem_to_mesh.f90, the source code.

Examples and Tests:

ELL is a 2D L-shaped region, with a grid of 65 nodes and 96 elements of order 3 triangles.

• ell_nodes.txt
• ell_elements.txt
• ell_elements.png, an image of the triangulation.
• ell_boundary_node_mask.txt
• ell.mesh, the MESH file.

P01 is 3D FEM data for a rectangular channel of dimensions 3x1x1 physical units, using 584 nodes and 2568 tetrahedral elements.

• p01_nodes.txt, defines the FEM nodes.
• p01_elements.txt, defines the FEM elements.
• p01.png, an image of the mesh.
• p01_boundary_node_mask.txt
• p01.mesh, the MESH file.

List of Routines:

• MAIN is the main program for FEM_TO_MESH.
• CH_CAP capitalizes a single character.
• CH_EQI is a case insensitive comparison of two characters for equality.
• CH_TO_DIGIT returns the integer ( kind = 4 ) value of a base 10 digit.
• FEM_DATA_READ reads data from a set of FEM files.
• FEM_HEADER_PRINT prints the header to set of FEM files.
• FEM_HEADER_READ reads the sizes of arrays in a set of FEM files.
• FEM_TO_MESH_HANDLE copies data from a FEM dataset to a MESH data set.
• FILE_COLUMN_COUNT counts the number of columns in the first line of a file.
• FILE_NAME_INC increments a partially numeric filename.
• FILE_ROW_COUNT counts the number of rows in a file.
• GET_UNIT returns a free FORTRAN unit number.
• I4MAT_DATA_READ reads data from an I4MAT file.
• I4MAT_HEADER_READ reads the header from an I4MAT.
• MESH_WRITE writes sizes and data to a MESH file.
• R8MAT_DATA_READ reads data from an R8MAT file.
• R8MAT_HEADER_READ reads the header from an R8MAT file.
• S_TO_I4 reads an integer ( kind = 4 ) value from a string.
• S_TO_I4VEC reads an integer ( kind = 4 ) vector from a string.
• S_TO_R8 reads an R8 from a string.
• S_TO_R8VEC reads an R8VEC from a string.
• S_WORD_COUNT counts the number of "words" in a string.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the FORTRAN90 source codes.