[ET Trac] #2549: inlcude FLRWSolver in ET

[Roland Haas]

#2549: inlcude FLRWSolver in ET

 Reporter: Roland Haas
   Status: new
Milestone: ET_2022_05
  Version: development version
     Type: enhancement
 Priority: major
Component: 

Comment (by Roland Haas):

Just catching up with things \(for half a day and then I will falling behind again\), I cannot comment on the actual physics. Certainly the description of the Courant factor is correct. There are certainly bits and pieces in the ET that will make assumptions like “lapse is about 1 at large radii” but those are mostly say gravitational wave extraction which is less useful in this situation \(since it also implicitly assumes a Schwarzschild like background for the waves\).

Having a large lapse should be fine, if I am not mistaken then eg Zach has a trick to smooth out initial gauge dynamics by temporarily setting a very large lapse even for black hole simulations \(though likely only near the black holes\). Anyway, the existing codes in the ET should \(fingers crossed\) all handle 0 < lapse < infty at least in cases where this makes sense.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2549/inlcude-flrwsolver-in-et
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