[CIG-SEISMO] CPML Boundary conditions, SPECFEM2D

[Dimitri Komatitsch]

Dear Anton,

You can use 
utils/CPML/convert_external_layers_of_a_given_mesh_to_CPML_layers2D.f90 
, which should do exactly what you need.

(if you need to slightly adapt it, please email me the modified version 
and I will add it to the official source code)

Let me also mention that program in the users manual.

Best regards,
Dimitri.

On 05/29/2015 04:42 PM, Anton Biryukov wrote:
>
> Good morning CIG Computational Seismology members,
>
>
>
> I am writing to you with a question about the CPML boundary
> condition implementation in the current version of SPECFEM2D code,
> available at geodynamics.org .
>
>
> Would you be so kind as to shed some light on how to implement the said
> conditions in the model?
>
>  From the manual I extracted two important bits of information :
>
>
> 1) Additional layers need to be created around the existing
> area-of-interest mesh, that should inherit the layered structure (if
> any) and be perfectly matching. This part is clear, and depends on my
> skill in creating a mesh with Gmsh.
>
>
> 2) Accordingly, changes need to be done in the Par File, to tell
> SPECFEM2D to use CPML instead of Stacey's conditions.
>
>
> Now, moving on to the parts that are not clear to me :
>
>
> a) The regular procedure of adapting an externally created mesh (in
> Gmsh) is to:
>
> - create a geometry
>
> - mesh it
>
> - assign specific identifiers to the physical surfaces that belong to
> different materials through commands like Physical Surface ("M1") =
> Surface{1}
> - assign specific identifiers to the boundaries ( e.g.  Physical
> Line("Top") = {1,2,3} )
> - run the python script provided by the developers, that digests the
> aforementioned .msh file and creates files, needed for xmeshfem2d to
> proceed.
>
>
> That works fine with me, and I managed to run the simulations using this
> approach. I was not quite happy with the numerical reflections though,
> so decided to fiddle with CPML a bit.
>
>
> b)  As I 've gone through the examples provided by developers, the CPML
> feature implementation becomes more and more vague to me ;
>
> Therefore, I am wondering whether :
>
> - I need to create additional physical surfaces and name them somehow
>
> - xmeshfem2d will understand the CPML layers in my mesh file
>
> -there is any script that will , analogous to the one I mentioned above
> for stacey's conditions, read the msh and output the necessary files, so
> I do not need to worry about them.
>
> - CPML files need to be created manually, and if yes, then what the
> easiest way would that be.
>
>
> I sincerely appreciate all the suggestions you might have for me,
>
>
>
> Best regards,
>
>
> Anton.
>
>
>
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>

-- 
Dimitri Komatitsch
CNRS Research Director (DR CNRS), Laboratory of Mechanics and Acoustics,
UPR 7051, Marseille, France    http://komatitsch.free.fr