Re: [Users] boundary conditions with Llama

Hello Miguel,

i now have a follow-up question... i would like to experiment with different boundary conditions, which i would like to implement myself. i had a look at LlamaWaveToy to see how it's implemented therein; would the following be a correct way of looping through the outer boundary points (assuming the boundary to be a spherical shell, as in LlamaWaveToy)?

reflevel = GetRefinementLevel(cctkGH) map = MultiPatch_GetMap(cctkGH) if (reflevel /= 0 .or. map == 0) return

do j = 1, cctk_lsh(2) do i = 1, cctk_lsh(1) do k = cctk_lsh(3)-cctk_nghostzones(3)+1, cctk_lsh(3) if (Sn(i,j,k) == -2) then

          [my BCs go here]

        end if
     end do
  end do

end do

Uhmm, probably not quite. The code should use the cctk_bbox(6) array which has entries 0 or 1 depending on whether a face is an outer (or symmetry) boundary or not.

The indexing is i = 1 + 2*idir + iface where idir = 0,1,2 and iface = 0,1 (lower, upper face).

The loops are kind of inefficient as you should have the "k" loop as the outer one (as usual). Using cctk_nghostzones(3) as the boundary width is not quite correct as technically you should use the boundary width returned by thorn CoordBase's GetBoundarySpecification aliased function (see its interface.ccl).

Yours, Roland