[Commits] [svn:einsteintoolkit] Paper_EinsteinToolkit_2010/ (Rev. 69)

[diener at cct.lsu.edu]

User: diener
Date: 2011/04/27 01:44 PM

Modified:
 /
  ET.tex

Log:
 Some stuff in relativity tools.

File Changes:

Directory: /
============

File [modified]: ET.tex
Delta lines: +25 -5
===================================================================
--- ET.tex	2011-04-27 18:39:57 UTC (rev 68)
+++ ET.tex	2011-04-27 18:44:41 UTC (rev 69)
@@ -1543,11 +1543,31 @@
 
 \subsection{Relativity Tools\pages{3 Peter}}
 
-\paragraph{Black Hole Excision}
+\subsubsection*{Vacuum-Matter Coupling}
+The thorn \codename{TmunuBase} provides grid functions for the stress-energy
+tensor $T_{\mu\nu}$ as well as schedule groups to manage when $T_{\mu\nu}$ is
+calculated.  In a simulation many different thorns may contribute to the
+stress-energy tensor and this thorn allows them to do so without explicit
+dependence on each other.  The resulting stress-energy tensor can then be used
+by the spacetime evolution thorn (again without explicit dependence on any
+matter thorns).  When thorn \codename{MoL} is used for time evolution this
+provides a high order spacetime-matter coupling.
 
-\paragraph{Vacuum-Matter Coupling}
+The grid functions provided by \codename{TmunuBase} are:
+\begin{itemize}
+ \item The time compenent $T_{00}$ {\tt eTtt}
+ \item The mixed components $T_{0i}$ {\tt eTtx}, {\tt eTty}, {\tt eTtz}
+ \item The spatial components $T_{ij}$ {\tt eTxx}, {\tt eTxy}, {\tt eTxz}, {\tt eTyy}, {\tt eTyz}, {\tt eTzz}
+\end{itemize}
+In addition the grid scalar {\tt stress\_energy\_state} has the value 1 if storage is on for the stress-energy tensor and 0 if not.
 
-\paragraph{Object tracking}
+
+Thorn \codename{ADMCoupling} provides a similar (but older) interface between
+space-time and matter thorns. However, since it is based on an include file
+mechansim it is more complicated to use and we recommend all new matter thorns
+to use \codename{TmunuBase} instead.
+
+\subsubsection*{Object tracking}
 \label{sec:object-tracking}
 We provide a module (\codename{PunctureTracker}) for tracking black hole
 positions when evolved with the moving puncture technique.  This can be used
@@ -1565,8 +1585,8 @@
 puncture location usually does not coincide with gridpoints, the shift is
 interpolated to the location of the puncture.  
 Equation~(\ref{eq:puncturetracking}) is implemented with a simple first order
-Euler scheme, which seems to be accurate enough for controlling the mesh
-refinement grids.
+Euler scheme, which seems to be accurate enough for controlling the location
+of the mesh refinement hierarchy.
 \todo{ES: I think this paragraph provides too much detail for this paper.}
 \todo{ES: Can also track objects via their maximum density or centre
   of mass; I believe GRHydro does something like this}