Aero-Structural Discrete Adjoint Sensitivities and Python Wrapper Developments

[patelha57]

Motivation

Fundamental bottlenecks exist for industrial adoption of high-fidelity physics codes with fully coupled discrete adjoint sensitivity analysis. These bottlenecks include a lack of flexibility, modularity, and robustness of the computational tools, as well as the potential startup development costs needed to implement and verify the MDAO features. The purpose of this work is to facilitate the coupling of SU2 with external structural codes (e.g. NASTRAN, TACS, Airbus structural suite Lagrange) for gradient-based aerodynamic shape and structural sizing optimization using dedicated frameworks (e.g. OpenMDAO).

Startup development costs include the creation of modular tools that are designed to be driven by another framework like OpenMDAO, rather than to drive execution themselves. However, leveraging those MDAO frameworks assumes that software codes and modules to be coupled exist, have appropriate data structures, execution and query APIs, and are wrapped in Python for flexibility and ease of use. The proposed changes were motivated with the goal of making SU2 more modular and flexible, particularly to facilitate its integration into large-scale MDAO frameworks. For more details on the motivation, methodology, and verification & validation results, please refer to our paper from AIAA Aviation 2022.

Proposed Changes

@aa-g and I propose the following code updates:

1. Implementation of residual-based discrete adjoint solver as CDiscAdjResidualSolver
   a. New config option: KIND_DISC_ADJ

2. Enhancements and standardization of SU2 Python API
   a. Add pysu2/pysu2ad methods
   b. Standardize Python API and function names
   c. Overloaded getter/setter methods to make data handling more flexible

Related Work

These efforts are related to Issue #1262, Pull Request #1300, and Discussion #1325.

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[pcarruscag]

Thank you, looks good to me, mostly just comments about naming conventions.

[patelha57]

@pcarruscag @bigfooted Finally seeing the light at the end of the tunnel on this PR... I added a regression test (which is passing) with an example that compares sens outputs from fixed-point and residuals adjoint solvers.

Anything else you want me to address on this?

[pcarruscag]

So this doesn't work if there is turbulence?

[patelha57]

Yes, I did not test with turbulence

[pcarruscag]

Do you have a test that exercises all the different cross terms?

[patelha57]

Do you have a test that exercises all the different cross terms?

You mean the aero-structural cross terms? If so, I don't have a SU2 specific test for those, since they were all handled by OpenMDAO