[CIG-SEISMO] different results deriving from SPECFEM2D with two mesh-create-methods (Cubit and Gmsh)

[Hu Jiupeng]

Hi,
I made another try with specfem2d version 7.0.0 to process the
model mentioned earlier and find some clues.
Though with the same msh-file (created by Gmsh program), the
specfem2d version 6.1.5 and version 7.0.0 give different results. And
the result obtained from version 7.0.0 with Gmsh meshes is very
similar to that from version 6.1.5 with Cubit meshes. A simple figure
attached shows these results.
I aslo checked the meshes using subprogram
xcheck_quality_external_mesh and get nothing abnormal like this:

(for  version 6 and 7, some distribution cause of the same msh-file used)
########################################################
  histogram of skewness (0. good - 1. bad):

  0.0000000      -   5.00000007E-02         329     14.954545      %
  5.00000007E-02  -   0.10000000             710     32.272728      %
  0.10000000      -   0.15000001             350     15.909091      %
  0.15000001      -   0.20000000             238     10.818182      %
  0.20000000      -   0.25000000             212     9.6363640      %
  0.25000000      -   0.30000001             135     6.1363635      %
  0.30000001      -   0.34999999              94     4.2727275      %
  0.34999999      -   0.40000001              76     3.4545455      %
  0.40000001      -   0.44999999              28     1.2727273      %
  0.44999999      -   0.50000000               6    0.27272728      %
  0.50000000      -   0.55000001               4    0.18181819      %
  0.55000001      -   0.60000002               5    0.22727273      %
  0.60000002      -   0.64999998               2    9.09090936E-02  %
  0.64999998      -   0.69999999               6    0.27272728      %
  0.69999999      -   0.75000000               5    0.22727273      %
  0.75000000      -   0.80000001               0     0.0000000      %
  0.80000001      -   0.85000002               0     0.0000000      %
  0.85000002      -   0.89999998               0     0.0000000      %
  0.89999998      -   0.94999999               0     0.0000000      %
  0.94999999      -    1.0000000               0     0.0000000      %
#########################################################


And as the "Max stability for P wave velocity" from the output_solver.txt,
both
version 6 and version 7 with Gmsh show this (same value, under the CFL
upper bound 0.697):

#########################################################
 *** Max stability for P wave velocity =   0.23151253858530865
#########################################################

So I suspect if the earlier version doesn't fit the Gmsh meshes well.
In addition, there  are still some slight differences between Gmsh and
Cubit
meshes for the same model (as show in figure attached). This may due to the
quality of the mesh?

Hu
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