THREED_TO_VTK
Write 3D Finite Element Data to VTK Legacy File

THREED_TO_VTK is a MATLAB program which accepts a certain set of 3D finite element data and writes it to a VTK legacy unstructured grid file for postprocessing by PARAVIEW.

A program which generates 3D finite element data of this type is available as NS3D_FEM; it uses the finite element method to solve the steady, incompressible Navier Stokes equations for fluid flow. THREED_TO_VTK makes it possible to examine this data graphically.

The finite element data is assumed to be given in terms of:

• the xyz coordinates of a set of nodes;
• the (1-based) indices of nodes that form tetrahedral elements;
• the values of U, V, W, and P at each node (velocity components and pressure).

Information about PARAVIEW is available at http://www.paraview.org/ .

Licensing:

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

Related Data and Programs:

NS3D_FEM, a MATLAB program which sets up and solves a finite element formulation of the steady incompressible 3D Navier Stokes equations on a user-defined geometry. The program can output graphics files for TECPLOT, VU or the VTK format used by PARAVIEW.

TET_MESH, a MATLAB library which carries out various operations on tetrahedral meshes.

TET_MESH_TET_NEIGHBORS, a MATLAB program which reads information about a tet mesh and writes out a list of the tetrahedrons that are adjacent to a given tetrahedron;

THREED, a MATLAB library which contains functions useful for 3D finite element calculations.

THREED_TO_TECPLOT, a MATLAB program which accepts computational data from a 3D finite element fluid flow program and writes it to a PLT file for postprocessing by TECPLOT.

THREED_TO_VTU, a MATLAB program which accepts computational data from a 3D finite element fluid flow program and writes it to a VTK unstructured grid file for postprocessing by PARAVIEW.

THREED_TO_VU, a MATLAB program which accepts computational data from a 3D finite element fluid flow program and writes it to a file for postprocessing by VU.

TWOD_TO_VTK, a MATLAB program which accepts computational data from a 2D finite element fluid flow program and writes it to a VTK "legacy" file for postprocessing by PARAVIEW.

VTK, a data directory which contains examples of VTK files, an obsolete file format used by the Visual Toolkit, and which can be displayed by the PARAVIEW program;

VTK_IO, a FORTRAN90 library which reads and writes files in the VTK format.

Author:

Jeff Borggaard,
Mathematics Department,
Virginia Tech.

Reference:

1. Will Schroeder, Ken Martin, Bill Lorensen,
   The Visualization Toolkit, An Object-Oriented Approach to 3D Graphics,
   Prentice Hall, 1998,
   ISBN: 0139546944,
   LC: QA76.64.S36.
2. Amy Henderson Squillacote,
   The ParaView Guide,
   Kitware Inc, 2007,
   ISBN13: 978-1-930934-21-4.
3. Will Schroeder, Ken Martin, Lisa Avila, Charles Law,
   The Visualization Toolkit User's Guide,
   Kitware Inc, May 2000,
   ISBN13: 978-1930934030.
4. http://public.kitware.com/VTK/

Source Code:

• timestamp.m, prints the YMDHMS date as a timestamp.
• vtk_puvw_write.m, writes pressure and 3D velocity vectors to a "legacy" VTK unstructured grid file.
• threed_to_vtk.m, accepts data in a THREED format, rearranges the data, and calls VTK_PUVW_WRITE to create the VTK file.

Examples and Tests:

• threed_to_vtk_test.m, a MATLAB function which runs a test of THREED_TO_VTK.

CASE1 is finite element data associated with a grid of points in a 1x1x5 rectangular channel, the tetrahdral elements formed from those nodes, and the velocity and pressure of an associated flow solution.

• case1_nodes.txt, the coordinates of the nodes;
• case1_elements.txt, the element definitions;
• case1_values.txt, the values of U, V, W and P at each node.
• case1.vtk, the legacy VTK file created from this data by the THREED_TO_VTK_TEST function.

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