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README
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Cactus Code Thorn ID_conerter_ILGRMHD
Author(s) : Zachariah B. Etienne
Note : Convert HydroBase variables to
IllinoisGRMHD-compatible variables. Used
for compatibility with HydroBase/ADMBase
initial data thorns in the Einstein
Toolkit.
Maintainer(s): Zachariah B. Etienne
License : FreeBSD License, AKA "2-Clause BSD License"
----------------------------------------------------------
1. Purpose
IllinoisGRMHD and HydroBase variables are incompatible;
The former uses 3-velocity defined as v^i = u^i/u^0, and
the latter uses the Valencia formalism definition of v^i.
Define the Valencia formalism's definition of v^i to be
"W^i", and IllinoisGRMHD's definition "v^i"
Then
W^i = (v^i + \beta^i) / (\alpha). (Eq 11 in
http://arxiv.org/pdf/1501.07276.pdf).
Similarly,
v_i = (\alpha) W^i - \beta^i
In addition, IllinoisGRMHD needs the A-fields to be
defined on *staggered* grids, and HydroBase does not yet
support this option. The staggerings are defined in
Table 1 of the IllinoisGRMHD code announcement paper:
http://arxiv.org/pdf/1501.07276.pdf (page 15).
The long-term goal should be to deprecate this thorn.