Dust in AstroBEAR - Update 2020/08/27

This is a mid-week summary of the past two weeks as I won't be around much for the next couple of weeks:

Objectives

  • Debugging the dust processing routines (Gas Drag, Sputtering, Grain-Grain Collisions)

Progress:

  • Gas Drag: I made a comparison between the different gas drag methods (collisional drag, plasma drag, collisional + plasma drag) which is available ​here. Bin 1 is doing weird stuff, not sure why so much material is left behind, need to check what's going on there. I'm also quite certain that the plasma drag is a bit too large. This might be due to the grain charge which I think is a factor 10 larger than it should be. Still tracking down why that is (probably a messed up constant somewhere).
  • Sputtering: I'm done with the first big debugging round of the sputtering routines. The bug that causes the crashes is fixed but I'm pretty sure I'm destroying too much dust at the moment (meaning my destruction rate is too high - probably again some faulty constant), and I'm still trying to fix the upper and lower collector bin: ​This is a simulation from earlier this week showing transport between the bins but weird stuff is going on in the upper and lower collector bin. Fixed the mass conservation and now I get ​this. Upper collector looks good but again I think destruction is progressing too quickly and obviously something is very wrong with the lower collector bin. Need to check whether that's a dust issue or a boundary/inflow issue. Also working on a plottings script to show the evolution of the total dust mass per bin across the entire domain to check whether the mass is indeed conserved or not.
  • Gas Feedback: Gas feedback for sputtering is done but I didn't run a simulation of it as it heavily relies on the lower collector bin to work and since that isn't the case yet there's little point in feeding faulty number densities back into the gas. But the basic principle is this: It is assumed that the material in the lower collector bin is dust sputtered to such a small grain size that the material can be considered gaseous. I then calculate the total mass in the collector bin, translate that to a number density of gas atoms and feed that back into the hydro gas while setting the content of the lower collector bin to 0 (or rather the minimum dust density).

Up Next:

  • Next three weeks: Probably won't get much coding done since I'm on break for a couple of days, then I need to finish the last stage of this year's HPC proposal and then I need to finish a thesis chapter. Might try to work on the collisions though if I get the chance.
  • More debugging for gas drag & sputtering + getting started with debugging the grain-grain collision routines
  • Gas feedback for gas drag + grain-grain collisions

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