[Commits] [svn:einsteintoolkit] GRHydro/trunk/src/ (Rev. 358)
rhaas at tapir.caltech.edu
rhaas at tapir.caltech.edu
Wed Jun 20 11:17:32 CDT 2012
User: rhaas
Date: 2012/06/20 11:17 AM
Modified:
/trunk/src/
GRHydro_HLLEM.F90
Log:
Change the characteristic speed for psidc.
It was set to +-c when it should be the maximum coming from the constraint
that the normal vector to the characteristic hypersurface of a wave
propagating along an arbitrary x direction be spacelike. This results
into the following bound for the wavespeed:
+- \alpha sqrt(\gamma^{xx}) - \beta^x)
Patch by Bruno Mundim.
File Changes:
Directory: /trunk/src/
======================
File [modified]: GRHydro_HLLEM.F90
Delta lines: +20 -5
===================================================================
--- trunk/src/GRHydro_HLLEM.F90 2012-06-20 16:16:52 UTC (rev 357)
+++ trunk/src/GRHydro_HLLEM.F90 2012-06-20 16:17:32 UTC (rev 358)
@@ -55,6 +55,7 @@
CCTK_REAL :: pressstarp,pressstarm,velxlowp,velxlowm,velylowp,velylowm,velzlowp,velzlowm
CCTK_REAL :: psidcp, psidcm, psidcf, psidcdiff, psidcfp, psidcfm
+ CCTK_REAL :: charmax_dc, charmin_dc, charpm_dc
CCTK_INT :: type_bits, trivial, not_trivial
@@ -440,13 +441,27 @@
end if
case(1)
!!$ Wavespeeds for psidc are +/-c, not Fast Magnetosonic?
- psidcf = 0.5d0 * (1.d0 * psidcfp - (-1.d0) * psidcfm + &
- 1.d0 * (-1.d0) * psidcdiff)
+ !!$ psidcf = 0.5d0 * (1.d0 * psidcfp - (-1.d0) * psidcfm + &
+ !!$ 1.d0 * (-1.d0) * psidcdiff)
+
+ !!$ The fastest speed for psidc comes from the condition
+ !!$ that the normal vector to the characteristic hypersurface
+ !!$ be spacelike (Eq. 60 of Anton et al.)
+
+ charmax_dc = sqrt(usendh) - avg_beta/avg_alp
+ charmin_dc = -1.d0*sqrt(usendh) - avg_beta/avg_alp
+ charpm_dc = charmax_dc - charmin_dc
+
+ psidcf = (charmax_dc * psidcfp - charmin_dc * psidcfm + &
+ charmax_dc * charmin_dc * psidcdiff) / charpm_dc
+
if(decouple_normal_Bfield .ne. 0) then ! same expression for HLLE and LLF
!!$ B^i field decouples from the others and has same propagation
- !!$ speed as divergence
- f1(5+flux_direction) = 0.5d0 * (1.d0 * fplus(5+flux_direction) - (-1.d0) * fminus(5+flux_direction) + &
- 1.d0 * (-1.d0) * qdiff(5+flux_direction))
+ !!$ speed as divergence -null direction,
+ !!$ \pm sqrt(g^{xx}} - beta^x/alpha
+ f1(5+flux_direction) = (charmax_dc * fplus(5+flux_direction) &
+ - charmin_dc * fminus(5+flux_direction) + &
+ charmax_dc * charmin_dc * qdiff(5+flux_direction)) / charpm_dc
end if
case(2)
charmax = setcharmax
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