Introduce a buffer zone between the prolongation destination and

Introduce a buffer zone between the prolongation destination and
restriction source grid points.  Set its width to 2 by default.  This
seems to be necessary for second order convergence.

darcs-hash:20030716194558-07bb3-d34ffc034cb54e4dcce2e2be2bd378184a79304e.gz

2 files changed, 10 insertions, 3 deletions

diff --git a/Carpet/CarpetLib/param.ccl b/Carpet/CarpetLib/param.ccl
index bba42acd0..707da6619 100644
--- a/Carpet/CarpetLib/param.ccl
+++ b/Carpet/CarpetLib/param.ccl
@@ -1,5 +1,5 @@
 # Parameter definitions for thorn CarpetLib
-# $Header: /home/eschnett/C/carpet/Carpet/Carpet/CarpetLib/param.ccl,v 1.3 2002/10/24 11:36:34 schnetter Exp $
+# $Header: /home/eschnett/C/carpet/Carpet/Carpet/CarpetLib/param.ccl,v 1.4 2003/07/16 21:45:58 schnetter Exp $
 
 private:
 
@@ -14,3 +14,8 @@ BOOLEAN barriers "Insert barriers at strategic places for debugging purposes (sl
 BOOLEAN output_bboxes "Output bounding box information to the screen"
 {
 } "no"
+
+CCTK_INT buffer_width "Width of the buffer zone between the prolongation destination and the restriction source"
+{
+  0:* :: "2 seems to be the minimum for second-order convergence"
+} 2
diff --git a/Carpet/CarpetLib/src/dh.cc b/Carpet/CarpetLib/src/dh.cc
index c9c15e1da..b140d68b4 100644
--- a/Carpet/CarpetLib/src/dh.cc
+++ b/Carpet/CarpetLib/src/dh.cc
@@ -1,4 +1,4 @@
-// $Header: /home/eschnett/C/carpet/Carpet/Carpet/CarpetLib/src/dh.cc,v 1.36 2003/07/14 15:41:34 schnetter Exp $
+// $Header: /home/eschnett/C/carpet/Carpet/Carpet/CarpetLib/src/dh.cc,v 1.37 2003/07/16 21:45:58 schnetter Exp $
 
 #include <assert.h>
 
@@ -281,7 +281,9 @@ void dh<D>::recompose (const int initialise_upto) {
                 boxes[rl  ][c ][ml].recv_ref_fine  [cc].push_back(recv);
               }
 #else
-              const ibbox recv = intrf.contracted_for(intr) & intr;
+              const ivect buf (buffer_width);
+              const ibbox recv = (intrf.contracted_for(intr).expand(-buf,-buf)
+                                  & intr);
               const ibbox send = recv.expanded_for(intrf);
               assert (send.empty() == recv.empty());
               if (! send.empty()) {