[Developers] patch: AEIThorns/BSSN_MoL: add new boundary option "nothing at all"

[Jonathan Thornburg]

Hi,

As of current CVS, AEIThorns/BSSN_MoL has a number of different
boundary options, all implemented via thorn Boundary.  Unfortunately,
* Boundary doesn't (yet) grok multiple patches: it aborts with a level-0
   error if an attempt is made to register multiple boundary conditions
   for the same face of "the" grid.
* BSSN_MoL schedules code in src/Constraints.F in local mode, so it
   will run once for each patch... and this code calls
    Boundary_SelectGroupForBC()  to register a boundary condition

I propose the enclosed patch to "fix" this behavior:

It adds a new option to BSSN_MoL::bound:

# if this next option is selected,
# this thorn completely skips all boundary processing,
# in particular it doesn't register anything with thorn Boundary
"nothing at all" :: "don't do any boundary processing at all"

and if this is selected, it skips the Boundary registration.


So far as I know, no existing code or par files are affected by this
change: the new option is *not* the default, and if not selected, the
existing behavior of this thorn is unchanged.


Are there any objections to my applying this patch?

ciao,

-- 
-- Jonathan Thornburg <jthorn at aei.mpg.de>
    Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut),
    Golm, Germany, "Old Europe"     http://www.aei.mpg.de/~jthorn/home.html
    "Washing one's hands of the conflict between the powerful and the
     powerless means to side with the powerful, not to be neutral."
                                       -- quote by Freire / poster by Oxfam
-------------- next part --------------
Index: param.ccl
===================================================================
RCS file: /numrelcvs/AEIThorns/BSSN_MoL/param.ccl,v
retrieving revision 1.19
diff -u -r1.19 param.ccl
--- param.ccl	29 Sep 2004 21:00:44 -0000	1.19
+++ param.ccl	14 May 2005 16:15:31 -0000
@@ -114,8 +114,14 @@
 
 KEYWORD bound "Boundary condition to implement"
 {
-  "flat"      :: "Flat boundary condition"
+  # if this next option is selected,
+  # this thorn completely skips all boundary processing,
+  # in particular it doesn't register anything with thorn Boundary
+  "nothing at all" :: "don't do any boundary processing at all"
+  # if any of the following options is selected,
+  # this thorn registers boundary conditions with thorn Boundary
   "none"      :: "No boundary condition"
+  "flat"      :: "Flat boundary condition"
   "static"    :: "Boundaries held fixed"
   "zero"      :: "Zero boundary condition"
   "minkowski" :: "Minkowski Dirichlet boundary condition"
Index: schedule.ccl
===================================================================
RCS file: /numrelcvs/AEIThorns/BSSN_MoL/schedule.ccl,v
retrieving revision 1.27
diff -u -r1.27 schedule.ccl
--- schedule.ccl	31 Jan 2005 14:36:58 -0000	1.27
+++ schedule.ccl	14 May 2005 16:15:31 -0000
@@ -283,6 +283,9 @@
     } "Trace A removal"
   }
 
+
+if (! CCTK_Equals(bound, "nothing at all"))
+{
   ####################################
   ###  BOUNDARY TERMS THE MOL WAY  ###
   ####################################
@@ -342,6 +345,7 @@
   schedule GROUP ApplyBCs as BSSN_MoL_ApplyBCs in ADM_BSSN_PostStep after ADM_BSSN_Boundaries
   {
   } "Apply boundary conditions controlled by thorn Boundary"
+}
 
   #########################################
   ### UPDATE THE STANDARD ADM VARIABLES ###
Index: src/Constraints.F
===================================================================
RCS file: /numrelcvs/AEIThorns/BSSN_MoL/src/Constraints.F,v
retrieving revision 1.5
diff -u -r1.5 Constraints.F
--- src/Constraints.F	8 Dec 2004 15:53:16 -0000	1.5
+++ src/Constraints.F	14 May 2005 16:15:31 -0000
@@ -89,9 +89,12 @@
 #include "macro/BSMOMSTD_undefine.h"
 #include "macro/BSGAMMA_undefine.h"
       
-      ierr = Boundary_SelectGroupForBC
-     $     (cctkGH, CCTK_ALL_FACES, 1, -1,
-     $     "ADM_BSSN::ADM_BSSN_cons", "Flat")
-      if (ierr/=0) call CCTK_WARN(0, "error trying to select Flat BC for ADM_BSSN::ADM_BSSN_cons")
+      if (.not. CCTK_Equals(bound, "nothing at all")) then
+          ierr = Boundary_SelectGroupForBC
+     $         (cctkGH, CCTK_ALL_FACES, 1, -1,
+     $         "ADM_BSSN::ADM_BSSN_cons", "Flat")
+          if (ierr/=0)
+     $       call CCTK_WARN(0, "error trying to select Flat BC for ADM_BSSN::ADM_BSSN_cons")
+      end if
       
       end subroutine ADM_BSSN_Constraints
Index: doc/documentation.tex
===================================================================
RCS file: /numrelcvs/AEIThorns/BSSN_MoL/doc/documentation.tex,v
retrieving revision 1.19
diff -u -r1.19 documentation.tex
--- doc/documentation.tex	8 Jan 2005 19:37:31 -0000	1.19
+++ doc/documentation.tex	14 May 2005 16:15:32 -0000
@@ -585,6 +585,9 @@
 ({\tt staticrad}) and also a generalization of the latter to improve
 the results in the case of a rotating frame ({\tt newrad}).
 
+There is also an option ({\tt "nothing at all"}) to skip all boundary
+processing; at present this is mainly useful for multipatch runs.
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 \begin{thebibliography}{10}