[WIP] Multizone adjoints for turbomachinery

[joshkellyjak]

Proposed Changes

This is a cleaned up PR of the fixes needed for multizone adjoints for turbomachinery from the previous PR of @oleburghardt and I's work.

This hopefully is useable, so if you would like to test and report please feel free to contact me on Slack.

TODO:

• Fix eddy viscosity tape issue in CNSSolver
• Add turbomachinery objective functions + constraints
• Include MZ testcase

Related Work

Now closed PR #2317

PR Checklist

Put an X by all that apply. You can fill this out after submitting the PR. If you have any questions, don't hesitate to ask! We want to help. These are a guide for you to know what the reviewers will be looking for in your contribution.

• [ X ] 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]

What is the difference between ending the preaccumulation before or after?

[pcarruscag]

Suggested change

	SU2_MPI::Error(string("OUTPUT_WRT_FREQ cannot be specified for this solver "
	SU2_MPI::Error("OUTPUT_WRT_FREQ cannot be specified for this solver "

[pcarruscag]

Hmmm I'm pretty sure it is possible

[joshkellyjak]

This is one for @oleburghardt

[oleburghardt]

Yes and no, writing the files is fine, but the continuation of the multi-zone discrete adjoint solver is erratic. My guess is that some indices aren't cleared properly before re-recording the tape. (Writing adjoint solution variables to file only, without re-recording at all and without sensitivities, might give us some hints.)
The debug mode could eventually pin down where exactly things go wrong.

[pcarruscag]

Why are these wrong but not the others that follow the same pattern?

[joshkellyjak]

This threw a tagging error, and if I remember correctly it's because in the other sections the variables it accesses are directly used in the solver, whereas in the Giles implementation they are not, creating a mismatch in tags.

[pcarruscag]

Can we fix it in a way that keeps a clear pattern for doing this type of thing?

[joshkellyjak]

I can give it a go

The best way to fix this problem is to remove the commented-out code entirely, since it serves no purpose for reading or maintenance of the code and may lead to confusion in the future. This entails deleting line 2750 from SU2_CFD/src/drivers/CDriver.cpp. No other changes are required to code logic or structure, because this is strictly the removal of unreachable/commented code that is not being used.

---

The best way to fix the problem is to remove the declaration of the unused local variable nSpanMax from function CDriver::PreprocessTurbomachinery in SU2_CFD/src/drivers/CDriver.cpp at line 2658. Only delete the specific line that declares nSpanMax; do not change other code or declarations unless they also reference nSpanMax (none appear to do so). This removal increases readability and avoids confusion about potential usage.

The most appropriate fix is to remove the commented-out code block at lines 604-613, since it is not being used and no context suggests it should be retained. This will reduce distraction and prevent future confusion. There is no indication that the code should be reinstated, and since similar functionality appears to already exist in the BroadcastData_MixingPlane call, deleting the commented block is safe and will not harm functionality.

• Remove lines 604–613 in SU2_CFD/src/drivers/CMultizoneDriver.cpp.
• No imports, methods, or redefinitions are needed.

---

To fix this problem, simply remove the unused local variable declaration for nDonorSpan at line 5584 from SU2_CFD/src/solvers/CEulerSolver.cpp. This involves deleting the line with the assignment. As no other code depends on this variable, this change is safe and does not alter any functionality or logic elsewhere. No imports, new methods, or definitions are necessary.

To fix the problem, we should rename the inner loop variable used at line 5586 (for (auto iVar = 0u; iVar < 8; iVar++)) to another unique name that does not shadow iVar declared at line 5477 in the function scope. The best approach is to pick a descriptive name such as mixVar, donorVar, or simply jVar, consistent with local naming convention.

Affected code region: SU2_CFD/src/solvers/CEulerSolver.cpp, lines around 5586-5588. We'll need to:

• Change for (auto iVar = 0u; iVar < 8; iVar++) { to use something like for (auto mixVar = 0u; mixVar < 8; mixVar++) {
• Change all references to iVar in that loop's body to use the new name: donorAverages[iVar] = GetMixingState(val_marker, iSpan, iVar); becomes donorAverages[mixVar] = GetMixingState(val_marker, iSpan, mixVar);

No imports or other changes are needed. Just update the index name in the local loop and its uses.

To fix the issue, we should rename the loop variable iVar on line 6289 to something distinctive, such as mixVar, so it does not shadow the previously declared function-scope variable iVar (from line 6170). This only requires changes within the for loop block associated with donor averages (lines 6289–6291).

Steps:

• Change the loop variable name in the for-loop header and update its references within the loop body accordingly.
• No need to change anything else, as this variable is only used for donor averages.

This change occurs only in the function CEulerSolver::BC_Giles within SU2_CFD/src/solvers/CEulerSolver.cpp, specifically between approximately lines 6289–6291.

To fix the issue, remove the declaration of the unused local variable nDonorSpan from line 1078 in SU2_CFD/src/solvers/CTurbSASolver.cpp.

• This improves readability and avoids a potential source of confusion or errors.
• Only remove the declaration itself—do not touch any other lines.
• No imports or further code changes are necessary, since the variable is not used or required elsewhere in the displayed code.

To address this commented-out code issue, the best course of action is to remove the commented-out code line entirely, as it appears to be a remnant from previous code iterations and does not serve a documentation or explanatory purpose. No changes to the implementation or functionality are required; simply deleting line 1081 from SU2_CFD/src/solvers/CTurbSASolver.cpp will resolve the issue and improve code clarity.

To fix this problem, we should remove the unused local variable nDonorSpan from the function CTurbSSTSolver::BC_Inlet_MixingPlane.

• Specifically, delete or comment out the line that declares and assigns nDonorSpan:

  auto nDonorSpan = solver_container[FLOW_SOL]->GetnMixingStates(val_marker, iSpan);

• This change is limited to a single line (line 806) within the function, and it will not affect any logic or required functionality because the variable is not accessed after being declared.
• No new imports, methods, or definitions are needed.

---

To fix the issue, we should remove the commented-out code lines, specifically lines 809 and 810 in SU2_CFD/src/solvers/CTurbSSTSolver.cpp. These lines don't serve as documentation, so they should be deleted, not reformatted. Only remove the lines that are exclusively commented-out code, making sure to retain surrounding code and comments that are not code. No imports, methods, or definitions need to be added or changed; it's a simple removal within the file.