Meeting Update 01/12/2015 - Eddie

2D Mach stems

See recent blog post: ehansen01092015

New results for gamma = 5/3:

movie​

I changed the density scale because I think this scale more clearly shows the Mach stems and post-shock regions. It appears that all 4 runs have Mach stems, but I only expected d = 12 and d = 11 to have them. It may be just because these separations are too close to the critical values. The d = 13 Mach stem shrinks and is very close to regular reflection which is expected. The d = 10 Mach stem grows and may be approaching the other limit where the bows merge. I'll have to run more models with d < 10 and d > 13 to really see the upper and lower limits.

movie​

I think it will be difficult to quantitatively prove or support Pat's calculations on maximum Mach stem formation angle. However, these simulations do clearly show, qualitatively, that a maximum angle does exist which explains why Mach stems grow and then disappear once the intersection goes above a certain angle.

It might be true that Mx approaches 1 at the triple point when a Mach stem just barely forms with the reflection shock still intact. This is at the maximum angle limit where the widest possible Mach stem forms. For this reason, I will be doing some more runs with gamma = 1.4 in hopes of finding and confirming this limit. So my runs will have separation distances between 4 and 5.5.


3D Mach stems

I completed a 3D run that will serve as the base comparison model. The emission map result is below:

movie​

This does look different than the previous run which can be seen at ehansen11252014. Fixing the initial ionization fraction changed things, but I don't know how much it is responsible for the differences.

Our initial plan was to explore the secondary bows that form behind the moving clump. I will investigate this by changing the clump velocity and/or the clump density. To start, I have a run going with twice the clump density.

This study will be somewhat slow moving because these runs each take about 2.5 days on 120 cores on bluehive. The files are also quite large (~500 GB per run), and disk space is limited on our local machines. For this reason, I will probably not save all of the chombos, so I will only show emission maps which come from the much smaller BOV files. Unless, anyone has a better idea to work around these issues?


Other Stuff

  • I have made progress on some development things that I will share tomorrow.
  • I started working on my Qualifying Brief, but I need to focus more on that for the next couple of weeks.

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