Meeting Update 09/29/2014 - Eddie

  • Did some interesting testing on velocity/momentum smoothing for clumps: ehansen09262014. What do we want to be the "correct" way? Should I remove velocity smoothing in our main development branch?
  • Tested the 3-D clump set up (see below)
  • Plan on doing 2.5-D pulsed jet paper revisions tonight.


3-D Clump

  • single clump (density contrast = 2000)
  • no cooling, gamma = 5/3
  • ambient/wind and clump in motion (M ~ 10)
  • velocity smoothing is still on
  • uses exact Riemann solver, linear interpolation, CFL = 0.5, 0.2, 0.5
  • effective resolution = 40 cells/rclump

Below is a 2-D slice of the density:

movie​

Still playing around with 3-D rendering. It takes a long time on my machine, so I may try using interactive jobs on bluehive from now on.

The above simulation completed 28.5/100 frames in 8 hours on 64 procs on Stampede. The remaining wall time estimates lead to a total run time of about 2 days for the entire 100 frames. On 64 procs, this is about 3000 SUs. Using Z cooling will at least double this to 6000. Adding a 2nd clump will generate more gradients and significantly increase run time (I'm guessing by a factor of at least 10). Best case scenario is that these runs take about 60,000 SUs at this low resolution of 40 cells/rclump.

I should also note that the above numbers are for a simulation time of 32.87 years, which seems reasonable when compared to observational time scales. Pat's HST observations show changes in emission features on even shorter time scales (~10 years). We may be able to improve resolution and run times if we limit our simulation parameters in such a way to make it easier on the code.

I spoke with Shule, and he said that his shocked clump simulations were at 64 cells/rclump, MHD, and took up to 2 days on 1024 procs on Kraken. So about 48,000 SUs. This seems much better than what I'm getting. It's hard to compare hydro + Z cooling vs. MHD + no cooling, but maybe if I tweak my parameters I can get up to this resolution.

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