Fix shared wall-inlet corner node for compressible #2266

bigfooted · 2024-04-16T21:42:28Z

TO DO:

bounded scalar seems to work correctly, last check to make sure
fix all regression tests

Proposed Changes

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Nodes shared by an inlet and a wall show nonphysical values in the corner node for energy, temperature, pressure, density. This fixes the issue

Related Work

Resolve any issues (bug fix or feature request), note any related PRs, or mention interactions with the work of others, if any.

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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.

bigfooted · 2024-04-16T21:48:30Z

@Cristopher-Morales Can you check if this fixes the issue for you? This works for the testcase that you gave me (2D compressible channel flow).
There is still a (compared to develop) very small local change in pressure but I think this is because at the inlet, the radial velocity is not zero and close to the wall the radial velocity component is not negligible, this is I think why the pressure locally is still not completely homogeneous.

bigfooted · 2024-04-16T21:57:52Z

Below is a zoom of the 2D flow in a rectangular channel. The flow is from left to right. The top side is a wall, the left side is the inlet. We are looking at the corner node shared by the inlet and the wall.
Pictures showing the Pressure for old (develop) and new implementation. The local pressure changes reduce by more than one order of magnitude:

Old and new energy near the corner:

Near the corner, the y-momentum (radial velocity) is not zero:

bigfooted · 2024-04-17T19:30:35Z

the user defined function case: a flat plate. top is with the fix, bottom (mirrored): the old develop.

bigfooted · 2024-04-20T14:21:18Z

@Cristopher-Morales can you check if bounded scalar works for you for this setup with compressible flow? I activated it and it seems to work fine for the small testcase that you sent. It is much better than scalar upwind.

bigfooted · 2024-04-20T14:35:29Z

Poiseuille flow, top is corrected, bottom is develop. There is still a small discrepancy in the energy but this might be due to the strong velocity components close to the wall.

bigfooted · 2024-04-20T14:37:34Z

SU2_CFD/include/solvers/CSpeciesSolver.hpp

+ /*!
+ * \brief Generic implementation of the isothermal wall also covering CHT cases,
+ * for which the wall temperature is given by GetConjugateHeatVariable.
+ */
+ void BC_Isothermal_Wall_Generic(CGeometry* geometry, CSolver** solver_container, CNumerics* conv_numerics,
+ CNumerics* visc_numerics, CConfig* config, unsigned short val_marker,
+ bool cht_mode = false);
+
+ /*!
+ * \brief Impose the scalar wall boundary condition.
+ * \param[in] geometry - Geometrical definition of the problem.
+ * \param[in] solver_container - Container vector with all the solutions.
+ * \param[in] conv_numerics - Description of the numerical method.
+ * \param[in] visc_numerics - Description of the numerical method.
+ * \param[in] config - Definition of the particular problem.
+ * \param[in] val_marker - Surface marker where the boundary condition is applied.
+ */
+ void BC_Isothermal_Wall(CGeometry* geometry, CSolver** solver_container, CNumerics* conv_numerics,
+ CNumerics* visc_numerics, CConfig* config, unsigned short val_marker) override;
+


I had to add this because scalar upwind for species transport in compressible flows showed a hard Dirichlet boundary condition of Y=0 on isothermal solid walls.

I have an idea why we see those results in the walls, we can discuss it this Tuesday.

Cristopher-Morales · 2024-04-20T14:46:07Z

@Cristopher-Morales can you check if bounded scalar works for you for this setup with compressible flow? I activated it and it seems to work fine for the small testcase that you sent. It is much better than scalar upwind.

Hi, yes it works much better, specially if we refine the mesh towards the walls.

SU2_CFD/src/solvers/CEulerSolver.cpp

@@ -1937,6 +1941,10 @@

 auto residual = numerics->ComputeResidual(config);

+ // this does not seem to be necessary
+ cout << "bounded" << endl;
+ //if (bounded_scalar) EdgeMassFluxes[iEdge] = residual[0];


SU2_CFD/src/solvers/CEulerSolver.cpp

@@ -1772,7 +1776,7 @@
 const bool muscl = (config->GetMUSCL_Flow() && (iMesh == MESH_0));
 const bool limiter = (config->GetKind_SlopeLimit_Flow() != LIMITER::NONE);
 const bool van_albada = (config->GetKind_SlopeLimit_Flow() == LIMITER::VAN_ALBADA_EDGE);
-
+ //const bool bounded_scalar = config->GetBounded_Scalar();


bigfooted · 2024-05-03T14:48:50Z

@EvertBunschoten can you check specifically the bounded scalar method? not sure if I missed something, see the comments that I left in the code.

GiuSirianni · 2024-05-13T10:31:05Z

I'm sorry to interject on this issue with what is probably a useless comment, but I wanted to ask if this issue affects you also in 1st order simulations?

In my experience MUSCL reconstruction at boundaries in SU2 is "incorrect" as it doesn't take into account the boundary condition applied and just assumed v_i = v_j, as far as I have understood from scouring the code. This usually is a small first order approximation locally, but with complex EoS or unlucky combinations of BCs and numerical settings it can cause unphysical solutions and crashes.

In a project of mine I have had some success by either disabling MUSCL outright at boundaries (very conservative and brutal solution), or disable it only at specific kinds of corners, which requires more memory unfortunately as one needs to somehow save if the node is a corner, etc.

The "real solution" would be to either save the boundary solution in ghost nodes and use it for the gradient computation, or fix gradients in post-process with a small performance penalty.

EvertBunschoten · 2024-05-13T12:26:48Z

It looks like the edge mass fluxes are not stored when running compressible RANS simulations, preventing any species convection when using BOUNDED_SCALAR. I'm looking into why this happens. Below is the species solution after 10 iterations for the passive_transport_validation test case for the RANS solver and using BOUNDED_SCALAR. The species values specified at the inlet do not progress downstream using the current settings.

bigfooted · 2024-05-13T19:15:36Z

Hi, @GiuSirianni, The problem I am addressing here is even more basic and occurs independent on the MUSCL scheme. When a corner is shared between an inlet and a wall, the inlet has to take into account that the node is shared by a wall (it has to know about no-slip for instance).
But it is good to know that MUSCL has issues at boundaries as well, this should definitely be fixed. If you can spare a couple of minutes, can you create an Issue here on github for MUSCL not being high order/robust on boundaries and share your experience?

GiuSirianni · 2024-05-15T09:24:16Z

@bigfooted I will open an issue, thank you!

bigfooted added 2 commits April 16, 2024 22:33

fix corner node

83e080c

fix corner node temp and dens

8624e0d

bigfooted added the changelog:fix label Apr 16, 2024

bigfooted requested a review from Cristopher-Morales April 16, 2024 21:46

bigfooted self-assigned this Apr 16, 2024

bigfooted added 2 commits April 17, 2024 00:09

fix warning for temperature maybe used uninitialized

f4f8a2b

move comment

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bigfooted added 3 commits April 18, 2024 20:08

Merge branch 'develop' into fix_cornernode_comp

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fix bounded scalar for compressible

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fix bounded scalar for compressible

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bigfooted commented Apr 20, 2024

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Cristopher-Morales added 2 commits April 21, 2024 16:39

Merge branch 'develop' into fix_cornernode_comp

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Merge branch 'develop' into fix_cornernode_comp

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bigfooted changed the title ~~[WIP] Fix shared wall-inlet corner node for compressible~~ Fix shared wall-inlet corner node for compressible Apr 24, 2024

Merge branch 'develop' into fix_cornernode_comp

c472e98

bigfooted requested a review from EvertBunschoten May 3, 2024 14:48

bigfooted and others added 3 commits May 13, 2024 21:15

Merge branch 'develop' into fix_cornernode_comp

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Merge branch 'develop' into fix_cornernode_comp

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Merge branch 'develop' into fix_cornernode_comp

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Cristopher-Morales added 3 commits May 16, 2024 08:44

Merge branch 'develop' into fix_cornernode_comp

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Merge branch 'develop' into fix_cornernode_comp

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Merge branch 'develop' into fix_cornernode_comp

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Fix shared wall-inlet corner node for compressible #2266

Fix shared wall-inlet corner node for compressible #2266

bigfooted commented Apr 16, 2024 •

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GiuSirianni commented May 15, 2024

Fix shared wall-inlet corner node for compressible #2266

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Fix shared wall-inlet corner node for compressible #2266

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bigfooted commented Apr 16, 2024 • edited

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