Add Scale Argument to VTK Export for Mesh Tally

[rherrero-pf]

Description

In many engineering workflows, the standard base unit is the meter. However, when exporting VTK files from a mesh tally in OpenMC, the default units often require manual rescaling in visualization tools like ParaView. This additional step can be time-consuming and error-prone, particularly in complex workflows.

To address this, a scale argument could be added to the VTK export functionality. This argument would allow users to specify a scaling factor directly during export, ensuring that the resulting mesh dimensions align with the desired unit system (e.g., meters). This feature would improve usability and eliminate the need for post-processing adjustments in external tools.

Alternatives

One alternative is to continue using ParaView’s built-in scaling function to adjust the mesh results.

Compatibility

Adding a scale argument with a default value of scale=1.0 would maintain backward compatibility with existing workflows.