Hi,
This issue is discussed for example in
http://arxiv.org/abs/1003.4681
where a non-constant damping in the gamma driver shift is presented to handle unequal mass binaries. As far as I remember there may also be later papers with further improvements to the method.
Cheers,
Peter
On Tuesday 2016-06-07 01:00, Frank Loeffler wrote:
Date: Tue, 7 Jun 2016 01:00:59 From: Frank Loeffler knarf@cct.lsu.edu To: rahul kashyap rahulkashyap411@gmail.com Cc: Einstein Toolkit Users users@einsteintoolkit.org Subject: Re: [Users] Resolving two BH
On Mon, Jun 06, 2016 at 06:50:04PM -0400, rahul kashyap wrote:
Thanks for the reply. My apologies that I'm not completely familiar many of the physical and numerical issues while simulating bbh. I have experience in AMR astrophysical simulations.
No need to apologize.
When I do the bbh simulation of ratio around 1, it evolves perfectly fine. With higher mass ratio, the smaller BH just becomes bigger and blows up. I'm assuming this as a problem of refinement.
It is not. It looks like what I described earlier: your gauge conditions, in particular the shift condition, isn't well suited for the small black hole. Grid points are "falling in", making it appear growing on the computational grid. You may try to play with the values such that the small black hole evolves fine (you can try that with a simulation of only a small black hole of that size), but then you might find that the large black hole "vanishes from the grid" because grid points there are pushed out too much. If this is the case, you might need position-dependent values.
Frank