On Oct 17, 2011, at 11:10 PM, Hee Il Kim wrote:
I'm doing the BNS test with magnetic fields but it's just in the
beginning stage. I don't know whether other people or the MHD
developers have done the test for the BNS. The BNS simulations with
the ET requires somewhat different setup from Whisky+BSSN_MoL.
I imagine you are using McLachlan for the Einstein equations, but what are the other differences? I presume you are also using PPM+HLLE. There is a difference between C2P in GRHydro and Whisky, but the rest should be similar I presume.
I'm
using a private thorn of Frank for the AMR. For the initial data, I
modified the public bns reader, Meudon_Bin_NS.
OK. If I were to do a comparison with Whisky I would use my thorns for ID and AMR.
Currently, I have little information on the best parameter setup for
the MHD. Please let me know if there's any special treatment required
for the MHD. Also I'd like to hear from Bruno on the initial B-field
data. Do I need anything more than I can expect from the initial
vector potential you used in the literatures?
the vector potential I used in my simulations is exactly the one that is mentioned in my papers (Giacomazzo et al 2009 and Giacomazzo et al 2011). Other people have used slightly different versions (Anderson et al 2008, Liu et al 2008). The vector potential I used for the initial data has the property of having also the first derivative of the magnetic field (B) going to zero when B goes to zero (i.e., it is more smooth than the one used in the other papers).
Cheers,
Bruno
Thanks in advance,
Hee Il
2011/10/18 Bruno Giacomazzo <
bruno.giacomazzo@jila.colorado.edu>:
Hi,
I have some questions about the MHD version of GRHydro. Today I had a
business meeting at the time of the telecon, otherwise I'd have asked them
during the telecon.
It is my understanding that the next release of the ET will happen next week
and it will contain MHD. Did you do already some tests in GR? Did you try
the evolution of BNS with magnetic fields? I'd like to try to run the code
with magnetized BNS and see how it compares with Whisky. As some of you know
in the past I had problems with divergence cleaning (DC) when evolving BNS
(strong violations of divB after the merger when the BH and the torus are
formed when using AMR) and so I'm curious to see if the implementation of DC
in GRHydro is more robust than the one I have in Whisky.
Thanks,
Bruno
P.S.: I will try to join the next ET telecon, so that I can get an update
before coming to LSU.
Dr. Bruno Giacomazzo
JILA - University of Colorado
440 UCB
Boulder, CO 80309
USA
Tel. : +1 303-492-0389
Fax : +1 303-492-5235
email : bruno.giacomazzo@jila.colorado.edu
web: http://www.brunogiacomazzo.org
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