Which Idea is Better for Achieving PML Boundary?

[zhangxiaoshuotttt]

@mloubout Hi,

Currently, the absorbing boundary is not efficient, especially when aiming for elastic or 3D FWI and LSRTM, as it requires a significant amount of grid space for the absorbing area.

Based on your tutorial, I would like to implement the PML boundary. While I find your method for achieving the absorbing boundary elegant, modifying the forward and adjoint formulas will be necessary for successfully implementing PML or HABC.

I have two ideas, and I would appreciate your guidance on them. I want to ensure that the PML can be utilized conveniently if I need to change my formulas again (please correct me if I'm wrong).

1. I could define a pml_stencil in the operators.py file and incorporate it within the ForwardOperator function, similar to the examples you've provided. However, the drawback of this approach is that if I wish to implement FWI or RTM, I will also need to modify other functions in the Operators module. Also, if I want to achieve another formula, I need to rewrite this.

2. Alternatively, can we achieve the PML functionality solely within the model.py? I'm considering adding the wavefield u as a parameter inside the Model function, allowing us to implement the PML based on this parameter. However, is this feasible ?I would like your insightful advice on this matter.

I am open to any other suggestions or comments you may have. Thank you for your time and patience.

Sincerely,
Shuo

[mloubout]

I would probably look at the first option. The Model is not really "propagation" related but more a plain representation of the subsurface irrespective of waves. The examples are more of a set of tutorial-ish propagators that can be used for research but you can use it as a skeleton for your own PDEs or go a separate ways if there is a design and interface that would fit your needs better.

PS:

I'm in and out for a few weeks, so apologies for the short answers

[zhangxiaoshuotttt]

Thank you for your insightful response. I also prefer the first option, as the second one is difficult for me to achieve.
I appreciate your time and assistance.