How to use xmeshfem2D with external model ?

[ICNSK]

Hi,
I am brand new user and trying to learn how to run xspecfem2D my research work. In the past I used finite difference simulators, which were limited to acoustic mode. I have input model for finite difference simulations, which is regularly samples binary file N1 x N2 and not sure how to convert it to mesh and model which could be used in xspecfem2D.

I was planning to use xmeshfem2D but could not find an example of how to use it with external mode.

Any information will be greatly appreciated, Thank you in advance

[mnagaso]

Hi,

For using the exernal model, you can modify this code and run with Par_file/MODEL = external :
https://github.com/SPECFEM/specfem2d/blob/master/src/specfem2D/define_external_model.f90

In your case, you can read your N1 x N2 model file in define_external_model subroutine, then you need to interpolate the grid coordinate into the specfem's nodes' position.

I hope this would help you,

[ICNSK]

Dear @mnagaso

Thank you very much for pointing me in the good direction ! I have limited experience programming in Fortran, but hopefully will be able to modify the define_external_model subroutine to implement functionality i need. As of now i am using 2 stage approach (generate proc***_rho_vp_vs.dat with "dummy" run with Par_file/SAVE_MODEL = ascii , unfortunately file is written at the end of simulation, than modify it using my binary file with material properties manually and run code second time with updated model using Par_file/Model = ascii )

[mnagaso]

Hi @ICNSK

Yes, your approach is also an alternative choice! I sometimes do that way actually if the mesh size is not so large. For the large mesh, it is better to do this with define_external_model. But the results should be identical with whichever way we use👍