COMMON ENVELOPE SIMULATIONS

New Work

  1. Notes about extracting diagnostics on accretion and drag force from the sim.
  2. Work on Xsede proposal.
  3. Improvement of high res run 132 to suppress unwanted extra refinement.

Summary of New Results

  1. Procedure to extract accretion and drag force diagnostics is now quite clear.
  2. Xsede proposal is coming along okay.
  3. Mysterious refinement to the max level was happening outside the volume for which the error flags are set to 1, slowing down the code. I couldn't prevent it by making changes to global.data so I decided to manually suppress it in problem.f90 (fortunately buffer zones turn out to be preserved).

Notes on accretion and drag force

Please see df.pdf

Discussion

  • There are a few issues that need to be discussed going forward:
    1. Type of accretion (Federrath+10 seems more appropriate to me than Krumholz+04)
    2. I've turned off particle creation—is this fine?
    3. Should we reduce the softening length and enhance the resolution with time as the particles get closer, as done by Ohlmann+16a? This seems reasonable except
      • do the gains justify the increase in resources?
      • is it really meaningful/beneficial/physical to change a "fuzzy" point particle into a less fuzzy point particle while the sim is in progress?
      • is it at least worth doing some tests to see what effect this would have?
    4. How important is it to use a larger box?
      • Maybe it would be enough to test this by doing one large-box run for comparison?

Next steps

  • Do for energy and angular momentum what has been done for accretion rate and drag force (see above notes).
  • Analysis of runs 136 (no relaxation), 120 (low density ambient medium) and 132 (high-res run, in progress)
  • New run with initial spin of RG at 95% Keplerian to test what difference this makes.
  • New run like run 088 (low res, twice the softening length of more recent runs) but with twice as high resolution (i.e. same resolution as current run 132) to test the convergence of results as the number of resolution cells per softening length increases (currently we know that 8 is insufficient and 17 may or may not be sufficient…here we would bump it up to 34).

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