CPML boundary conditions

[samyog111]

Hello,
I am currently working on a seismic wave propagation model with dimensions of 4x1x384 meters (x,y,z). Initially, I applied Stacey boundary conditions, which resulted in a correct waveform shape, although being incorrect with a phase shift compared to analytical solution or numerical solutions from FLAC. To address these phase issues, I attempted to implement CPML boundary conditions. Note: I want to apply freefield/periodic conditions on the right side, absorbing conditions on the base, and free surface at the top.

I initially used the automatic CPML size generated by the function add_CPML_layers from the utils section, but unfortunately, it did not execute successfully. Subsequently, I applied a CPML size less than 30% of the size along X,Y,Z direction, which allowed the model to run. However, the results significantly differed from those obtained with the Stacey boundary conditions, particularly in waveform shape.

In the Stacey setup, I had removed the absorbing conditions on the sides and only applied them at the base, which proved effective in generating the waveform shape as Ricker wavelet. However, the CPML did not yield the same success with Stacey.

Attached are the results from the CPML boundary conditions for your review. Could you provide guidance on how to adjust the CPML implementation to achieve waveform results comparable to those with Stacey boundary conditions? In addition, could you please tell me how to apply free field/periodic boundary conditions on the side? Any insights or suggestions would be greatly appreciated.

Regards,
Samyog

[samyog111]

Results from Stacey: