GRHydro: correct atmosphere handling after primitve reconstruction

I have fixed a bug in GRHydro's atmosphere handling after reconstruction.
After reconstruction, the reconstructed plus and minus face values are tested
for whether they drop below atmosphere level and are then reset.  In
particular, this means that plus and minus face values for cell i don't
generally coincide with the minus/plus face values of the corresponding cells
i-1 and i+1.  If the reconstruction previously found that the Riemann problem
was trivial between, say rhominus(i+1) and rhoplus(i), when changing
rhoplus(i), it is not anymore!  However, the mask "trivial_rp" testing for a
trivial Riemann problem is not changed!  This leads to inconsistent behavior at
the boundary of the atmosphere.

The symptom was a drift in the center of mass of a static and perfectly
symmetric TOV star.

Patch by Christian Reisswig.


git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinEvolve/GRHydro/trunk@332 c83d129a-5a75-4d5a-9c4d-ed3a5855bf45

1 files changed, 33 insertions, 8 deletions

diff --git a/src/GRHydro_Reconstruct.F90 b/src/GRHydro_Reconstruct.F90
index c35afec..f10bc71 100644
--- a/src/GRHydro_Reconstruct.F90
+++ b/src/GRHydro_Reconstruct.F90
@@ -44,6 +44,7 @@ subroutine Reconstruction(CCTK_ARGUMENTS)
 
   CCTK_INT  :: i,j,k
   CCTK_REAL :: local_min_tracer
+  CCTK_INT :: type_bits, not_trivial
 
   ! save memory when MP is not used
   CCTK_INT :: GRHydro_UseGeneralCoordinates
@@ -83,12 +84,30 @@ subroutine Reconstruction(CCTK_ARGUMENTS)
     end if
   end if
 
+
+  if (flux_direction == 1) then
+    call SpaceMask_GetTypeBits(type_bits, "Hydro_RiemannProblemX")
+    call SpaceMask_GetStateBits(not_trivial, "Hydro_RiemannProblemX", &
+         &"not_trivial")
+  else if (flux_direction == 2) then
+    call SpaceMask_GetTypeBits(type_bits, "Hydro_RiemannProblemY")
+    call SpaceMask_GetStateBits(not_trivial, "Hydro_RiemannProblemY", &
+         &"not_trivial")
+  else if (flux_direction == 3) then
+    call SpaceMask_GetTypeBits(type_bits, "Hydro_RiemannProblemZ")
+    call SpaceMask_GetStateBits(not_trivial, "Hydro_RiemannProblemZ", &
+         &"not_trivial")
+  else
+    call CCTK_WARN(0, "Flux direction not x,y,z")
+  end if
+
   !$OMP PARALLEL DO PRIVATE(i,j,k)
-     do k=1,cctk_lsh(3)
-        do j=1,cctk_lsh(2)
-           do i=1,cctk_lsh(1)
-              if(rhoplus(i,j,k).lt.GRHydro_rho_min .or. &
-                   rhominus(i,j,k).lt.GRHydro_rho_min) then
+  do k = GRHydro_stencil, cctk_lsh(3) - GRHydro_stencil + 1
+    do j = GRHydro_stencil, cctk_lsh(2) - GRHydro_stencil + 1
+      do i = GRHydro_stencil, cctk_lsh(1) - GRHydro_stencil + 1
+         if(rhoplus(i,j,k).lt.GRHydro_rho_min .or. &
+            rhominus(i,j,k).lt.GRHydro_rho_min) then
+
                  rhoplus(i,j,k)  = rho(i,j,k)
                  rhominus(i,j,k) = rho(i,j,k)
                  epsplus(i,j,k)  = eps(i,j,k)
@@ -107,10 +126,15 @@ subroutine Reconstruction(CCTK_ARGUMENTS)
                    tracerminus(i,j,k,:) = tracer(i,j,k,:)
                 end where
              end if
-          enddo
-       enddo
+             ! Riemann problem might not be trivial anymore!!!!
+             SpaceMask_SetStateBitsF90(space_mask, i-xoffset, j-yoffset, k-zoffset, type_bits, not_trivial)
+             SpaceMask_SetStateBitsF90(space_mask, i, j, k, type_bits, not_trivial)
+      enddo
     enddo
-    !$OMP END PARALLEL DO
+  enddo
+  !$OMP END PARALLEL DO
+  
+
 
   if (CCTK_EQUALS(recon_vars,"primitive").or.&
        CCTK_EQUALS(recon_method,"ppm")) then
@@ -133,3 +157,4 @@ subroutine Reconstruction(CCTK_ARGUMENTS)
 
 end subroutine Reconstruction
 
+