Actuator source passive scalar and tagging

[marchdf]

Summary

This revives capability that was showcased in #474 but never merged. This lets us have a passive scalar that is initialized at the actuator source location and advect/diffuse.

All credit goes to @michaeljbrazell for this. I just renamed things and simplified.

Pull request type

Please check the type of change introduced:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Checklist

The following is included:

• new unit-test(s)
• new regression test(s)
• documentation for new capability

This PR was tested by running:

• the unit tests
  • on GPU
  • on CPU
• the regression tests
  • on GPU
  • on CPU

Additional background

This lets us have a passive scalar that is initialized at the actuator source location and advect/diffuse. We can do 2 things with this:

1. visualize the wake with in situ methods: we can hook up in-situ viz capability to take isosurfaces and visualize the wakes
2. we can do refinement based on this: we can add a tagging criteria on this field which will refine the wake.

Here's a demo viz:

This introduces a bunch of knobs:

1. tagging.tracer.field_error: what value do you decide is high enough that you should refine
2. transport.passive_scalar_laminar_schmidt and transport.passive_scalar_turbulent_schmidt for diffusion of this passive scalar
3. ActuatorSourceTagging.act_src_threshold at what source value threshold do we have a unity passive scalar

I have no idea what those values should be but we could study that.

[mbkuhn]

looks good to me! will be a cool feature.