Concerns Regarding the Coupling Between MOOSE and External Programs

[Blackfoxdragon]

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Question

I've done some minor development within the MOOSE framework and find its functionality excellent. I intend to continue using it and hope to integrate it with my own program. Specifically, I still want MOOSE to serve as the main framework, calling my program during computations or simulations to obtain results, which would then be passed to other MOOSE modules to achieve data exchange.

The current issue is that I'm unsure how to proceed. A bigger problem is that my own program is written in Fortran, which is not the same programming language as MOOSE itself. I also don't fully understand how MOOSE's program interface works.

While gathering information, I noticed the Cardinal program, but it doesn't seem to provide much better inspiration. I'm wondering if there are any more concrete examples or literature from a programming perspective that could help me learn how MOOSE interacts with external programs, especially those written in an older language like Fortran.

[GiudGiud]

Hello

I've done some minor development within the MOOSE framework and find its functionality excellent.

Thanks for the praise! We hope you can meet your modeling goals with it.

Specifically, I still want MOOSE to serve as the main framework, calling my program during computations or simulations to obtain results, which would then be passed to other MOOSE modules to achieve data exchange.

Ok so deciding that MOOSE will run the show is the first important decision for how to couple with external codes.
If MOOSE is in control, then the path forward is creating wrapped applications

The current issue is that I'm unsure how to proceed. A bigger problem is that my own program is written in Fortran, which is not the same programming language as MOOSE itself. I also don't fully understand how MOOSE's program interface works.

That's ok, we can compile fortran in the Makefile. I m trying to find an open source example and get back to you

While gathering information, I noticed the Cardinal program, but it doesn't seem to provide much better inspiration. I'm wondering if there are any more concrete examples or literature from a programming perspective that could help me learn how MOOSE interacts with external programs, especially those written in an older language like Fortran.

Cardinal is a great example for coupling MOOSE with other C++ applications that are completely external. The executioner classes specifically show how to run that external solve, calling the APIs in these codes from MOOSE.
And the transfers class to move data from MOOSE to these applications and back.

[GiudGiud]

So there are at least 3 example directly in MOOSE:
UMAT and UEL:
https://mooseframework.inl.gov/source/materials/abaqus/AbaqusUMATStress.html

Thermochimica integration:
https://github.com/idaholab/moose/blob/next/modules/chemical_reactions/contrib/thermochimica.mk

[Blackfoxdragon]

Thank you！I will try it

[Blackfoxdragon]

Thank you for your help. I'm gradually getting back on track now.
I have a few other questions I'd like to ask. My Fortran external program requires a different mesh setup than MOOSE (MOOSE uses a finer 3D mesh, while the external program uses a coarser one). I'd like to understand how to implement and write the data exchange between these two mesh systems. I noticed that the thermochimica example you provided doesn't seem to involve mesh data interaction. If there are other concrete examples, that would be very helpful. Additionally, I'm curious whether this data transfer might impact the overall parallel performance of the program?

[GiudGiud]

Hello

You will find examples of custom transfers between an external app mesh (nekRS) and a MOOSE mesh in Cardinal.

With regards to parallel performance, the transfers could need to be written in a distrivuted/parallel manner for performance with many processes.

However our experience so far has been that transfers are quite fast compared to solving numerical systems. It is possible you would be fine just replicating the external app coarse solution and writing a transfer in serial executing on every process (replicated).