ParaView and CTH

CTH datasets

This tutorial shows how to visualize CTH datasets (called spcth files). CTH is a multi-material, large deformation, strong shock wave, solid mechanics code developed at Sandia National Laboratories. A more complete writeup on CTH is here: http://www.sandia.gov/CTH/. CTH Spyplot files are Eulerian, or structured mesh datasets. They can be flat mesh or adaptive mesh refinement (i.e., AMR).

• This tutorial assumes that the user is already farmiliar with ParaView. If necessary, see tutorials https://www.paraview.org/Wiki/Beginning_ParaView and https://www.paraview.org/Wiki/Beginning_Sources_and_Filters.

A bit of background

Exodus datasets are often Lagrangian, or unstructured mesh. CTH creates datasets that are Eulerian, or structured mesh. Unstructured meshes move with the object. If you have a bumper that hits a tree, the bumper and mesh will wrap around the tree. Structured meshes remain fixed, and represent their data with variables that describe how much of a material is in each cell. If a structured mesh has a bumper hit a tree, the bumper will move through the mesh, with variables changing from 0% bumper to 100% bumper, and back to 0% bumper. This is called a Volume Fraction, generally running from 0 to 1 (0% to 100%). Rectilinear meshes have all cells stacked side by side in a 3d cube. If there is no refinement, this is called a flat mesh. Structured meshes can have areas of refinement, giving us a larger number of smaller cells where the action is. This is called an AMR structured mesh (Adaptive Mesh Refinement).

A simple CTH AMR example

Our goal is to create a contour where Material Volume Fractions go from under 10% to over 10%.

• Start ParaView.

• Open spcta_a.0.[0-3]. Turn all variables on. Apply.
• Filters/ CTH/ Extract CTH Parts. Turn off all Volume Arrays, except Material volume fraction - 1. Apply.
• In the Pipeline Browser, select Volume Data (i.e., the raw cth data again).
• Filters/ CTH/ Extract CTH Parts. Turn off all Volume Arrays, except Material volume fraction - 2. Apply.
• Paint by Pressure.
• Play forward.

Acknowledgements

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.