daniellivingston / exodus-polyhedra

Building Exodus

A Makefile is provided to ease to process of building Exodus. Just run:

make exodus

and it will be downloaded to ./seacas/ and built. You will need CMake 3.10+, gcc and g++.

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It may take up to 45 minutes for Exodus to compile, depending on network speeds and machine specs.

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For issues with compiling Exodus or running this makefile, contact Daniel Livingston at [email protected].

Configuring the Python examples

Python scripts are included in the py-lib directory. These are used to create 3D Exodus meshes.

These scripts were written by Ethan Coon as part of the Amanzi/ATS project and can originally be found here.

Configuring python-exodus

This script uses the Exodus Python library to make calls to the compiled C library.

To get Python to find the exodus-python package, either append the SEACAS library path to your PYTHONPATH:

export PYTHONPATH=$PYTHONPATH:$(pwd)/seacas/lib

Or set the SEACAS_DIR environment variable:

export SEACAS_DIR=$(pwd)/seacas

Also, export the environment variable ACCESS, which Exodus uses internally:

export ACCESS=$(pwd)/seacas

Running the Python examples

Reference meshes for the two examples can be found in the output/ directory.

Four Polygon Test

cd four-polygon-test
python2.7 ../py-lib/meshing_ats.py -n 10 -d 1 ./four_polygon.vtk

This will read in the 2D mesh four_polygon.vtk and extrude and write to four_polygon.exo.

Basic Example

cd py-lib
python2.7 basic_ats_example.py

This will use Numpy to generate a simple mesh in meshing_ats_example.exo.

Polyhedra elements in Exodus

Exodus supports Polyhedra elements, these are made up of element vertices, the faces composed of vertices, and the elements composed of faces. The 3D polyhedra elements are represented as elements with a variable number of faces in their connectivity. The faces can either be regular faces such as quadrilateral or triangles; or they can be topologically two-dimensional arbitrary polyhedra themselves.

See example descriptions in the /output directory containing example Exodus .exo files.

Exodus documentation on polyhedral elements: https://gsjaardema.github.io/seacas/html/polyhedra.html

Visualizing Exodus files

ParaView or VisIT can be used to view the Exodus files.