I am trying to set up a binary black hole simulation that uses 8th order accurate finite differencing. (I need the black holes to be highly resolved, and I don't need the wave zone, thus I am not use AMR.) On the other hand, I am using Cartoon2D, and I extended it to support 8th order interpolation.
My problem is that I cannot get the simulation started well. After a few (about 70) time steps, the code aborts due to nans. Of course, having modified thorn Cartoon2D, I cannot exclude that I made an error there. On the other hand, I did find some pre-existing errors that I corrected.
I wonder: What are good settings for numerical dissipation in this case (ML_BSSN with fdOrder=8)? I see a sample parameter file that uses epsDiss = 0.1; should I expect this to work? Would puncture initial conditions need any kind of special treatment? (I'm using TwoPunctures.)
Thanks, -erik