Implementation of DDES and SAS formulations for SST #2150

rois1995 · 2023-10-22T16:16:37Z

Proposed Changes

Hi everyone,

I have been working on the implementation of the DDES formulations for the SST model, following the work in "Development of DDES and IDDES Formulations for the k-ω Shear Stress Transport Model" (DOI:10.1007/s10494-011-9378-4). The implementation is easy, whereas the validation may take some time. I am currently working on the backward facing step and I will work on the flatplate too. The choice of the validation test cases is key since the computational cost is quite large, thus if you have any suggestions that may speed up this part then feel free to write them down.

Implemented versions:

SST-DDES
SST-IDDES
SST-SIDDES

I am also working on the Scale Adaptive Simulations (SAS) implementations for SST, following the work in "ON URANS SOLUTIONS WITH LES-LIKE BEHAVIOUR", Travis et al., and "[Evaluation of scale-adaptive simulation for transonic cavity flows", Babu et al., (https://www.inderscienceonline.com/doi/abs/10.1504/IJESMS.2016.075510). The last one, especially, is quite tricky due to the computation of the velocity laplacian. I tried computing it in Paraview as the divergence of the gradient field and it seems quite similar, but it is the first time that I've touched that section of the code, thus some work might still be needed.

Implemented versions:

SST-SAS_Simple (better naming is necessary), from the article of Travis et al.
SST-SAS_Complicated (better naming is necessary), it is related to the article from Babu et al.

PR Checklist

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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.

…ons based on k and w - Added computation of k and w starting from SA variables - Added first implementation of SAS (Scale Adaptive Simulation) model

- Changed previous SAS model to SAS_SIMPLE

- Fixed DataType for Periodic Comms

…lified IDDES (SIDDES)

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

pcarruscag · 2023-10-24T07:50:37Z

Common/include/option_structure.hpp

+  SAS_SIMPLE,         /*!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. */
+  SAS_COMPLICATED,         /*!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. */


Are these the names in the literature?

No, these are just placeholders. There are no names in literature, that is why I named them according to the complexity of the model

Maybe something after the authors since the models come from different papers.

Sure, why not

pcarruscag · 2023-10-24T07:52:24Z

Common/include/option_structure.hpp

+  SST_OPTIONS sasModel = SST_OPTIONS::SAS_SIMPLE;   /*!< \brief Enum SST base model. */
  bool sust = false;                          /*!< \brief Bool for SST model with sustaining terms. */
  bool uq = false;                            /*!< \brief Bool for using uncertainty quantification. */
+  bool sas = false;                           /*!< \brief Bool for using Scale Adaptive Simulations. */


Probably the type is enough and "none" indicates no sas.

Suggested change

SST_OPTIONS sasModel = SST_OPTIONS::SAS_SIMPLE; /*!< \brief Enum SST base model. */

bool sust = false; /*!< \brief Bool for SST model with sustaining terms. */

bool uq = false; /*!< \brief Bool for using uncertainty quantification. */

bool sas = false; /*!< \brief Bool for using Scale Adaptive Simulations. */

SST_OPTIONS sasModel = SST_OPTIONS::NONE; /*!< \brief Enum SST base model. */

bool sust = false; /*!< \brief Bool for SST model with sustaining terms. */

bool uq = false; /*!< \brief Bool for using uncertainty quantification. */

Sure, I'll modify it.

pcarruscag · 2023-10-24T07:53:10Z

Common/src/CConfig.cpp

+          case SST_DDES: cout << "Delayed Detached Eddy Simulation (DDES) with Shear-layer Adapted SGS" << endl; break;
+          case SST_IDDES: cout << "Delayed Detached Eddy Simulation (DDES) with Shear-layer Adapted SGS" << endl; break;
+          case SST_SIDDES: cout << "Delayed Detached Eddy Simulation (DDES) with Shear-layer Adapted SGS" << endl; break;


The description is slightly different right?

Yes, I planned to modify the details on the final implementation. I'll do it now

pcarruscag · 2023-10-24T07:54:33Z

SU2_CFD/include/numerics/CNumerics.hpp


+  su2double lengthScale_i, lengthScale_j;
+  su2double FTrans;   /*!< \brief SAS function */
+  su2double VelLapl_X, VelLapl_Y, VelLapl_Z;


Use a matrix type for the laplacian in CVariable and here you can have a pointer instead.
Put these variables close to other turbulence variables please.

I think the main problem with my implementation is that the norm of the velocity laplacian stated in the paper is $||U''||=\sqrt{\sum_i \left( \frac{\partial^2 U_i}{\partial x_j \partial x_j}\right)^2}$ and I am not sure that this is what I am computing. Do I need to store a matrix for each velocity component, compute it as gradient of the gradient and then sum the traces of each matrix?

That looks like the norm of the Laplacian of the velocity components, the way you are computing it is not very accurate but maybe it is good enough. You could do it the finite volume way by reusing the numerics classes we use for scalar viscous fluxes.

pcarruscag · 2023-10-24T07:56:34Z

SU2_CFD/include/numerics/turbulent/turb_sources.hpp

+        su2double VelLaplMag = VelLapl_X*VelLapl_X + VelLapl_Y*VelLapl_Y;
+        if (nDim == 3) VelLaplMag += VelLapl_Z*VelLapl_Z;
+        const su2double L_vK_1 = KolmConst * StrainMag_i / sqrt(VelLaplMag);


Is the velocity laplacian only used for the source term? Or will you have changes to the convection or diffusion fluxes?

It is just for the source term

pcarruscag · 2023-10-24T08:00:36Z

SU2_CFD/include/variables/CTurbSAVariable.hpp

+  /*!
+   * \brief Get the value of the turbulence kinetic energy.
+   * \return the value of the turbulence kinetic energy.
+   */
+  inline su2double GetSSTVariables_k(unsigned long iPoint) const { return k(iPoint); }
+
+  /*!
+   * \brief Get the value of the turbulence frequency Omega.
+   * \return the value of the turbulence frequency Omega.
+   */
+  inline su2double GetSSTVariables_omega(unsigned long iPoint) const { return Omega(iPoint); }
+
+  /*!
+   * \brief Set the value of the SST variables computed with SA solution.
+   * \param[in] val_k
+   * \param[in] val_Omega
+   */
+  void SetSSTVariables(unsigned long iPoint, su2double val_k, su2double val_Omega) {
+    k(iPoint) = val_k;


Are these changes related to the main theme? or were just debugging? If they can be separated to another PR let's do that please.

These are for computing the grid size for scale resolving simulations from an SA solution. Probably it has to be revised a little bit, since I found out that the formulation for the TKE is different if the QCR mod is used, thus I think I'll remove them for now.

pcarruscag · 2023-10-24T08:10:12Z

externals/codi

You need to undo this change to the codi version.

Sure, I'll do it

SU2_CFD/src/output/CFlowOutput.cpp

pcarruscag · 2023-10-24T08:12:52Z

SU2_CFD/src/output/CFlowOutput.cpp

+    }
+    const su2double mut = Node_Flow->GetEddyViscosity(iPoint);
+    const su2double mu = Node_Flow->GetLaminarViscosity(iPoint); 
+    const su2double LESIQ = 1.0/(1.0+0.05*pow((mut+mu)/mu, 0.53));


Are the constant here also used somewhere else? It would be good to avoid repeating hard-coded constants

They are used just here

pcarruscag · 2023-10-24T08:14:22Z

SU2_CFD/include/variables/CVariable.hpp

+  inline virtual su2double GetVelLapl_X(unsigned long iPoint) const { return 0.0; }
+  /*!
+   * \brief Get the value of the value of FTrans.
+   */
+  inline virtual su2double GetVelLapl_Y(unsigned long iPoint) const { return 0.0; }
+  /*!
+   * \brief Get the value of the value of FTrans.
+   */
+  inline virtual su2double GetVelLapl_Z(unsigned long iPoint) const { return 0.0; }
+
+  /*!
+   * \brief Set the value of the value of FTrans.
+   */
+  inline virtual void AddVelLapl(unsigned long iPoint, su2double val_VelLapl_X, su2double val_VelLapl_Y) {}
+  /*!
+   * \brief Set the value of the value of FTrans.
+   */
+  inline virtual void AddVelLapl_Z(unsigned long iPoint, su2double val_VelLapl_Z) {}
+  /*!
+   * \brief Set the value of the value of FTrans.
+   */
+  inline virtual void SetVelLapl(unsigned long iPoint, su2double val_VelLapl_X, su2double val_VelLapl_Y) {}


Use a pointer for velocity and then you only need one of each function instead of handling xyz separately.

Yeah, I'll try using the matrix type

- Changed names of SAS models - Added descriptions of functions - Clean up of output functions - Removed SA functions or SST variables

SU2_CFD/include/numerics/CNumerics.hpp

SU2_CFD/src/output/CFlowOutput.cpp

pcarruscag · 2023-11-01T18:23:24Z

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+        /*--- If iPoint is boundary it only takes contributions from other boundary points. ---*/
+        if (boundary_i && !boundary_j) continue;
+
+        /*--- Add solution differences, with correction for compressible flows which use the enthalpy. ---*/


Check if comments need updates please

bigfooted · 2024-02-07T15:48:09Z

Hi @rois1995 any progress? Would be very interesting to add this to develop, looking forward to using it actually.

rois1995 · 2024-03-07T13:31:32Z

Hi @rois1995 any progress? Would be very interesting to add this to develop, looking forward to using it actually.

Hi @bigfooted, unfortunately I do not have enough time/computational power to perform a proper validation. I only tried something with a NACA0021 at 17 deg and 60 deg and they were promising, at least for the DDES implementation. The SAS ones are not that good. I'll upload some post-processing as soon as I have the time to do so.

Linnnnnn23 · 2024-04-19T07:54:55Z

I find your work really interesting. I've been studying the internal flow field in compressors and have had good results using SU2's SA_EDDES for calculating the cantilevered stator with a tip clearance. If you need help with code verification, I'd be glad to assist.

rois1995 · 2024-04-23T08:49:06Z

I find your work really interesting. I've been studying the internal flow field in compressors and have had good results using SU2's SA_EDDES for calculating the cantilevered stator with a tip clearance. If you need help with code verification, I'd be glad to assist.

Hi @Linnnnnn23, every help on the validation/verification is gladly accepted! Let me know if you need anything by my side.

Linnnnnn23 · 2024-04-23T11:30:53Z

I find your work really interesting. I've been studying the internal flow field in compressors and have had good results using SU2's SA_EDDES for calculating the cantilevered stator with a tip clearance. If you need help with code verification, I'd be glad to assist.

Hi @Linnnnnn23, every help on the validation/verification is gladly accepted! Let me know if you need anything by my side.
Thank you for your response. Firstly, I would like to know what Verification and Validation (V&V) work has been conducted on the SST-based DDES (Delayed Detached Eddy Simulation) model to date. Secondly, we can provide a compressor cascade validation, with an inlet Mach number of 0.4, a Reynolds number of approximately 500,000, and a spanwise height of about 20% of the chord length, ensuring that the vortices resolved by DDES can develop in three dimensions. Thirdly, as I am a rookie to GitHub, I have not yet found out how to download your pull request code. For further communication, you can contact me via email at [email protected]

BerkeCan97 · 2024-10-24T08:34:32Z

Hi @rois1995 , I'd like to help with validation/verification if I can. Let me know if you are interested. You can contact me at [email protected].

BerkeCan97 · 2024-10-30T12:59:03Z

Hi @rois1995 any progress? Would be very interesting to add this to develop, looking forward to using it actually.

Hi @bigfooted, unfortunately I do not have enough time/computational power to perform a proper validation. I only tried something with a NACA0021 at 17 deg and 60 deg and they were promising, at least for the DDES implementation. The SAS ones are not that good. I'll upload some post-processing as soon as I have the time to do so.

Hi @rois1995, I believe there is an error or a typo in the Babu's paper in the Q_SAS source term and in turn in your implementation, which may be the reason for the poor performance in SAS results.

This term changes units depending on the output of the max function, which doesn't make any sense. I believe the terms in the max function should be divided by omega^2 and k^2 instead of omega and k, respectively. Which is exactly how it is done in https://resolver.tudelft.nl/uuid:5d23e2a6-5675-450d-bf3d-1dd40d736cae

I will try some of the benchmark cases in these papers when I have the time. Let me know what you think.

[edit: fixed the link to the tudelft repository]

SU2_CFD/include/numerics/turbulent/turb_sources.hpp

rois1995 · 2025-04-09T18:17:36Z

It seems that the problem is encountered on skew elements on periodic boundaries. I have tried running the SA-EDDES simulation for 30 timesteps with only one inner iteration (the problem remains when running for one temporal iteration with 30 inner iterations).

Periodic boundary

Center plane

The same problem remains with SA-URANS simulation.

Periodic boundary SA-URANS

The problem does not appear if Symmetry BCs are used instead of Periodic BCs.

EDIT:

I have tried with the SA-EDDES model and the problem still persists even with symmetry BCs, although it appears a little bit later.

pcarruscag · 2025-07-05T22:16:27Z

Is this one ready for review @rois1995 or still testing?

rois1995 · 2025-07-07T07:44:09Z

Hi @pcarruscag, I am not planning on running other tests for now, I think that the results are good enough. For me, it is ready for review. Should I remove the debug variables/outputs before reviewing?

pcarruscag · 2025-07-07T15:02:41Z

Yep please remove debug stuff

pcarruscag

Nice additions 👍

pcarruscag · 2025-07-07T15:03:29Z

Common/include/option_structure.hpp

+  SAS_TRAVIS,         /*!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. */
+  SAS_BABU,         /*!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. */


pcarruscag · 2025-07-07T15:03:55Z

Common/include/option_structure.hpp

+  const bool sst_sas_travis = IsPresent(SST_OPTIONS::SAS_TRAVIS);
+  const bool sst_sas_babu = IsPresent(SST_OPTIONS::SAS_BABU);
+  if (sst_sas_travis && sst_sas_babu) {
+    SU2_MPI::Error("Two versions (Simple and Complicated) selected for SAS under SST_OPTIONS. Please choose only one.", CURRENT_FUNCTION);


Update simple and complicated?

pcarruscag · 2025-07-07T15:04:08Z

Common/include/option_structure.hpp

+  SA_EDDES = 4,           /*!< \brief Kind of Hybrid RANS/LES (SA - Delayed DES (DDES) with Shear Layer Adapted SGS: Enhanced DDES). */
+  SST_DDES = 5,           /*!< \brief Kind of Hybrid RANS/LES (SST - Delayed DES (DDES): DDES). */
+  SST_IDDES = 6,           /*!< \brief Kind of Hybrid RANS/LES (SST - Delayed DES (DDES): Improved DDES). */
+  SST_SIDDES = 7,           /*!< \brief Kind of Hybrid RANS/LES (SST - Delayed DES (DDES): Simplified Improved DDES). */
+  SST_EDDES = 8,           /*!< \brief Kind of Hybrid RANS/LES (SST - Delayed DES (DDES): Enhanced (SLA) DDES). */


pcarruscag · 2025-07-07T15:05:37Z

SU2_CFD/include/numerics/CNumerics.hpp

+  su2double FTrans;   /*!< \brief SAS function */
+  su2double Q_SAS_1;   /*!< \brief SAS function */
+  su2double Q_SAS_2;   /*!< \brief SAS function */
+  su2double L;   /*!< \brief SAS function */
+  su2double L_vK_1;   /*!< \brief SAS function */
+  su2double L_vK_2;   /*!< \brief SAS function */


If these were here for debugging, please use local variables in the function where these quantities are used.

pcarruscag · 2025-07-07T15:06:17Z

SU2_CFD/include/numerics/turbulent/turb_sources.hpp


      su2double dk = beta_star * Density_i * ScalarVar_i[1] * ScalarVar_i[0] * (1.0 + zetaFMt);
+      if (config->GetKind_HybridRANSLES() != NO_HYBRIDRANSLES)
+        dk = Density_i * sqrt(ScalarVar_i[0]*ScalarVar_i[0]*ScalarVar_i[0]) / lengthScale_i;


Suggested change

dk = Density_i * sqrt(ScalarVar_i[0]*ScalarVar_i[0]*ScalarVar_i[0]) / lengthScale_i;

dk = Density_i * sqrt(pow(ScalarVar_i[0], 3)) / lengthScale_i;

pcarruscag · 2025-07-07T15:30:19Z

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+        const su2double weight = halfOnVol;
+
+        const auto area = geometry->edges->GetNormal(iEdge);
+        AD::SetPreaccIn(area, nDim);


This is not doing anything because you are not starting/ending the preaccumulation.

pcarruscag · 2025-07-07T15:31:49Z

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+    switch(kind_hybridRANSLES){
+      case SST_DDES: {
+


Can you add some links to the references you used for each formulation? (here or somewhere you think is more appropriate)

pcarruscag · 2025-07-07T15:33:57Z

SU2_CFD/src/variables/CTurbVariable.cpp

+  Omega = sqrt(Vorticity[0]*Vorticity[0] + Vorticity[1]*Vorticity[1]+ Vorticity[2]*Vorticity[2]);
+
+  StrainDotVort[0] = Strain[0][0]*Vorticity[0]+Strain[0][1]*Vorticity[1]+Strain[0][2]*Vorticity[2];
+  StrainDotVort[1] = Strain[1][0]*Vorticity[0]+Strain[1][1]*Vorticity[1]+Strain[1][2]*Vorticity[2];
+  StrainDotVort[2] = Strain[2][0]*Vorticity[0]+Strain[2][1]*Vorticity[1]+Strain[2][2]*Vorticity[2];
+
+  numVecVort[0] = StrainDotVort[1]*Vorticity[2] - StrainDotVort[2]*Vorticity[1];
+  numVecVort[1] = StrainDotVort[2]*Vorticity[0] - StrainDotVort[0]*Vorticity[2];
+  numVecVort[2] = StrainDotVort[0]*Vorticity[1] - StrainDotVort[1]*Vorticity[0];
+
+  numerator = sqrt(6.0) * sqrt(numVecVort[0]*numVecVort[0] + numVecVort[1]*numVecVort[1] + numVecVort[2]*numVecVort[2]);
+  trace0 = 3.0*(pow(Strain[0][0],2.0) + pow(Strain[1][1],2.0) + pow(Strain[2][2],2.0));
+  trace1 = pow(Strain[0][0] + Strain[1][1] + Strain[2][2],2.0);
+  denominator = pow(Omega, 2.0) * sqrt(trace0-trace1);


Geometry toolbox where possible please

pcarruscag · 2025-07-07T15:35:10Z

SU2_CFD/src/variables/CTurbVariable.cpp

+  Strain[0][0] = PrimGrad_Flow[1][0];
+  Strain[1][0] = 0.5*(PrimGrad_Flow[2][0] + PrimGrad_Flow[1][1]);
+  Strain[0][1] = 0.5*(PrimGrad_Flow[1][1] + PrimGrad_Flow[2][0]);
+  Strain[1][1] = PrimGrad_Flow[2][1];
+  if (nDim == 3){
+    Strain[0][2] = 0.5*(PrimGrad_Flow[3][0] + PrimGrad_Flow[1][2]);
+    Strain[1][2] = 0.5*(PrimGrad_Flow[3][1] + PrimGrad_Flow[2][2]);
+    Strain[2][0] = 0.5*(PrimGrad_Flow[1][2] + PrimGrad_Flow[3][0]);
+    Strain[2][1] = 0.5*(PrimGrad_Flow[2][2] + PrimGrad_Flow[3][1]);
+    Strain[2][2] = PrimGrad_Flow[3][2];


Don't we have a helper function for this somewhere? Maybe in the viscous fluxes?

I see that there is a ComputeMeanRateOfStrainMatrix in CNumerics, I will use that.

pcarruscag · 2025-07-07T15:36:51Z

SU2_CFD/src/variables/CTurbVariable.cpp

+  AD::SetPreaccIn(PrimGrad_Flow, nDim+1, nDim);
+  AD::SetPreaccIn(Vorticity, 3);
+  /*--- Eddy viscosity ---*/
+  AD::SetPreaccIn(muT(iPoint));
+  /*--- Laminar viscosity --- */
+  AD::SetPreaccIn(LaminarViscosity);
+
+  Strain[0][0] = PrimGrad_Flow[1][0];


We need to abstract the index for velocity somehow, otherwise this is not compatible with the NEMO solver.
Maybe change PrimGrad_Flow to VelGrad and whoever call this function is responsible by passing the correct part of the gradients.

pcarruscag · 2025-07-07T15:38:28Z

Can you add a regression test?
Something of V&V quality (which you have already I think) would be awesome even if you don't have time to do a full write up on it.

rois1995 · 2025-07-23T10:34:59Z

I will definitively add a V&V case, although I do not have time at the moment. I will also review the suggestions as soon as possible.

- Made Get/SetSRSGridSize non virtual

- Used GeometryToolbox when possible

SU2_CFD/include/variables/CVariable.hpp

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+    switch(kind_hybridRANSLES){
+      /*--- Every model is taken from "Development of DDES and IDDES Formulations for the k-ω Shear Stress Transport Model"
+                                      Mikhail S. Gritskevich et al. (DOI:10.1007/s10494-011-9378-4)
+        ---*/
+      case SST_DDES: {
+
+        const su2double r_d = (eddyVisc + lamVisc) / max((KolmConst2*wallDist2 * sqrt(0.5 * (StrainMag*StrainMag + VortMag*VortMag))), 1e-10);
+        const su2double C_d1 = 20.0;
+        const su2double C_d2 = 3.0;
+
+        const su2double f_d = 1 - tanh(pow(C_d1 * r_d, C_d2));
+
+        const su2double l_LES = C_DES * h_max;
+
+        DES_lengthScale = l_RANS - f_d * max(0.0, l_RANS - l_LES);
+
+        break;
+      }
+      case SST_IDDES: {
+
+        // Constants
+        const su2double C_w = 0.15;
+        const su2double C_dt1 = 20.0;
+        const su2double C_dt2 = 3.0;
+        const su2double C_l = 5.0;
+        const su2double C_t = 1.87;
+
+        const su2double alpha = 0.25 - sqrt(wallDist2) / h_max;
+        const su2double f_b = min(2.0 * exp(-9.0 * alpha*alpha), 1.0);
+        const su2double r_dt = eddyVisc / max((KolmConst2*wallDist2 * sqrt(0.5 * (StrainMag*StrainMag + VortMag*VortMag))), 1e-10);
+        const su2double f_dt = 1 - tanh(pow(C_dt1 * r_dt, C_dt2));
+        const su2double ftilda_d = max(1.0 - f_dt, f_b);
+
+        const su2double r_dl = lamVisc / max((KolmConst2*wallDist2 * sqrt(0.5 * (StrainMag*StrainMag + VortMag*VortMag))), 1e-10);
+        const su2double f_l = tanh(pow(C_l*C_l*r_dl, 10.0));
+        const su2double f_t = tanh(pow(C_t*C_t*r_dt, 3.0));
+        const su2double f_e2 = 1.0 - max(f_t, f_l);
+        const su2double f_e1 = alpha >= 0.0 ? 2.0 * exp(-11.09*alpha*alpha) : 2.0 * exp(-9.0*alpha*alpha);
+        const su2double f_e = f_e2 * max((f_e1 - 1.0), 0.0);
+
+
+        const su2double Delta = min(C_w * max(sqrt(wallDist2), h_max), h_max);
+        const su2double l_LES = C_DES * Delta;
+
+        DES_lengthScale = ftilda_d *(1.0+f_e)*l_RANS + (1.0 - ftilda_d) * l_LES;
+
+        break;
+      }
+      case SST_SIDDES: {
+
+        // Constants
+        const su2double C_w = 0.15;
+        const su2double C_dt1 = 20.0;
+        const su2double C_dt2 = 3.0;
+
+        const su2double alpha = 0.25 - sqrt(wallDist2) / h_max;
+        const su2double f_b = min(2.0 * exp(-9.0 * alpha*alpha), 1.0);
+        const su2double r_dt = eddyVisc / max((KolmConst2*wallDist2 * sqrt(0.5 * (StrainMag*StrainMag + VortMag*VortMag))), 1e-10);
+        const su2double f_dt = 1 - tanh(pow(C_dt1 * r_dt, C_dt2));
+        const su2double ftilda_d = max(1.0 - f_dt, f_b);
+
+        const su2double Delta = min(C_w * max(sqrt(wallDist2), h_max), h_max);
+        const su2double l_LES = C_DES * Delta;
+
+        DES_lengthScale = ftilda_d*l_RANS + (1.0 - ftilda_d) * l_LES;
+
+        break;
+      }
+      case SST_EDDES: {
+
+        // Improved DDES version with the Shear-Layer-Adapted augmentation 
+        // found in Detached Eddy Simulation: Recent Development and Application to Compressor Tip Leakage Flow, Xiao He, Fanzhou Zhao, Mehdi Vahdati
+        // originally from Application of SST-Based SLA-DDES Formulation to Turbomachinery Flows, Guoping Xia, Zifei Yin and Gorazd Medic
+        // I could be naming it either as SST_EDDES to follow the same notation as for the SA model or as SST_SLA_DDES to follow the paper notation
+
+        const su2double f_max = 1.0, f_min = 0.1, a1 = 0.15, a2 = 0.3;
+
+        const auto nNeigh = geometry->nodes->GetnPoint(iPoint);
+
+        su2double vortexTiltingMeasure = nodes->GetVortex_Tilting(iPoint);
+
+        su2double deltaOmega = -1.0;
+        su2double vorticityDir[MAXNDIM] = {};
+
+        for (auto iDim = 0; iDim < MAXNDIM; iDim++){
+          vorticityDir[iDim] = Vorticity[iDim]/VortMag;
+        }
+
+        for (const auto jPoint : geometry->nodes->GetPoints(iPoint)){
+          const auto coord_j = geometry->nodes->GetCoord(jPoint);
+
+          for (const auto kPoint : geometry->nodes->GetPoints(iPoint)){
+            const auto coord_k = geometry->nodes->GetCoord(kPoint);
+
+            su2double delta[MAXNDIM] = {};
+            for (auto iDim = 0u; iDim < MAXNDIM; iDim++){
+              // TODO: Should I divide by 2 as I am interested in the dual volume (the edge is split at midpoint)?
+              delta[iDim] = (coord_j[iDim] - coord_k[iDim])/2.0; 
+            }
+            su2double l_n_minus_m[MAXNDIM];
+            GeometryToolbox::CrossProduct(delta, vorticityDir, l_n_minus_m);
+            deltaOmega = max(deltaOmega, GeometryToolbox::Norm(3, l_n_minus_m));
+          }
+
+          // Add to VTM(iPoint) to perform the average
+          vortexTiltingMeasure += nodes->GetVortex_Tilting(jPoint);
+        }
+        deltaOmega /= sqrt(3.0);
+        vortexTiltingMeasure /= (nNeigh+1);
+
+        const su2double f_kh = max(f_min,
+                                   min(f_max,
+                                       f_min + ((f_max - f_min)/(a2 - a1)) * (vortexTiltingMeasure - a1)));
+
+        const su2double r_d = (eddyVisc + lamVisc) / max((KolmConst2*wallDist2 * sqrt(0.5 * (StrainMag*StrainMag + VortMag*VortMag))), 1e-10);
+        const su2double C_d1 = 20.0;
+        const su2double C_d2 = 3.0;
+
+        const su2double f_d = 1 - tanh(pow(C_d1 * r_d, C_d2));
+
+        su2double delta = deltaOmega * f_kh;
+        if (f_d < 0.99){
+          delta = h_max;
+        }
+
+        const su2double l_LES = C_DES * delta;
+        DES_lengthScale = l_RANS - f_d * max(0.0, l_RANS - l_LES);
+      }
+    }


To fix the long case, we should extract the entirety of the logic inside the case SST_EDDES: block (lines 1169–1228) into a dedicated private helper method, e.g., CalcLengthScaleSST_EDDES(...). All the variables that this logic needs—locals from the function, members, and parameters from the loop—must be passed as parameters if they aren't accessible as class members. In this case, nearly all dependent variables are either available in the class or in function scope from the loop, or can be passed explicitly (typical parameters: indices, node pointers, relevant variables).

We'll insert the helper as a private method in the class' source file, just before or after SetDES_LengthScale, and replace the original content of case SST_EDDES: with a single call to this function. No changes to declarations in header files are required if marked as private/protected for internal use (some projects prefer explicitly listing such helpers in the header; however, only the implementation file is available, so we’ll keep all changes local).

SU2_CFD/src/variables/CTurbVariable.cpp

- Rearrenged and renamed outputs

- Remove unused variables

rois1995 · 2025-10-03T10:39:34Z

Should we allow DDES to be run on 2D meshes? The DDES flatplate testcase has a 2D mesh, but it does not really make any sense to run 2D cases with DDES.

pcarruscag · 2025-10-03T15:06:19Z

If someone is determined enough they'll make a 2.5D mesh and still run it 😄
Maybe you can just print a big warning but allow it to run? It could be useful for regression tests.
Is there anything in the implementation that only works for 3D?

rois1995 · 2025-10-06T12:45:51Z

I am pretty sure that the EDDES models have something that does not work in 2D, like the vortex-tilting measure (depends on the scalar product of the gradient of the velocity and the vorticity, thus in 2D it should be zero).

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+
+        const su2double f_max = 1.0, f_min = 0.1, a1 = 0.15, a2 = 0.3;
+
+        const auto nNeigh = geometry->nodes->GetnPoint(iPoint);


To fix the problem, we should rename one of the nNeigh declarations to prevent variable shadowing. Since the outer nNeigh (line 1080) is defined at the start of the large loop and is used more broadly, it is best to rename the inner declaration (line 1178, inside the SST_EDDES case clause) to a distinct name such as nNeigh_EDDES.

Steps:

Locate the inner declaration at line 1178: const auto nNeigh = geometry->nodes->GetnPoint(iPoint);

Change it to, e.g., const auto nNeigh_EDDES = geometry->nodes->GetnPoint(iPoint);

Update any usage of nNeigh within this case SST_EDDES block to nNeigh_EDDES.

No new methods, imports, or definitions are required, just a rename for clarity.

SU2_CFD/src/solvers/CTurbSSTSolver.cpp

+
+        const su2double f_max = 1.0, f_min = 0.1, a1 = 0.15, a2 = 0.3;
+
+        const auto nNeigh = geometry->nodes->GetnPoint(iPoint);


To fix the variable shadowing, the best approach is to rename the inner variable declared at line 1238 within the case SST_EDDES_UNSTR: block to a distinct and descriptive name, e.g., nNeigh_case or something more reflective of its purpose within the block. This avoids hiding the nNeigh variable declared at line 1080 in the surrounding loop. Only the definition at line 1238, and any subsequent usages of it within the same case block, should be renamed. No functionality should be changed—only variable naming within the shown code region. No changes to imports or class definitions are needed.

rois1995 and others added 11 commits September 15, 2023 09:21

- Added computation of desired grid size for Scale Resolving Simulati…

388f85a

…ons based on k and w - Added computation of k and w starting from SA variables - Added first implementation of SAS (Scale Adaptive Simulation) model

- Added a more complex SAS model named SAS_COMPLICATED

41cb27e

- Changed previous SAS model to SAS_SIMPLE

- Fixed getting coordinates of points

a6be2cf

- Fixed DataType for Periodic Comms

- Added output of laplacian

d1f4db6

- Fixed missing variable initialization for CTurbSAVariable

35958b8

- Added DES implementations to SST: DDES, Improved DDES (IDDES), Simp…

09e977f

…lified IDDES (SIDDES)

- Added SST DDES in config

8c8e89d

- Added Debug quantities

71ac9c4

- Added division by 0 protection

5b5fc30

- Added computation of LESIQ to Output

ef50283

Merge branch 'develop' into feature_SST_IDDES

91c742e

github-advanced-security bot found potential problems Oct 22, 2023

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SU2_CFD/src/solvers/CTurbSSTSolver.cpp Fixed Show fixed Hide fixed

SU2_CFD/src/solvers/CTurbSSTSolver.cpp Fixed Show fixed Hide fixed

rois1995 added 2 commits October 23, 2023 19:07

Merge 'origin/feature_SAS' into feature_SST_IDDES

6c86a19

- modified codi

48a9f3d

rois1995 changed the title ~~[WIP] Implementation of DDES formulations for SST~~ [WIP] Implementation of DDES and SAS formulations for SST Oct 23, 2023

pcarruscag reviewed Oct 24, 2023

View reviewed changes

- Modified Velocity Laplacian (vector -> Matrix)

ae33b05

- Changed names of SAS models - Added descriptions of functions - Clean up of output functions - Removed SA functions or SST variables

pcarruscag reviewed Nov 1, 2023

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bigfooted added the changelog:feature label Nov 12, 2023

rois1995 added 3 commits September 20, 2024 09:37

- Added outputs log for SST-DDES

6443070

Merge remote-tracking branch 'origin/develop' into feature_SST_IDDES

caf0d41

- update externals

a584526

BerkeCan97 reviewed Oct 30, 2024

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SU2_CFD/include/numerics/turbulent/turb_sources.hpp Outdated Show resolved Hide resolved

- Added come outputs

8f3efae

rois1995 force-pushed the feature_SST_IDDES branch from 625ecb0 to 8f3efae Compare June 10, 2025 17:52

- minor fix

f716218

Merge remote-tracking branch 'origin/develop' into feature_SST_IDDES

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pcarruscag reviewed Jul 7, 2025

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rois1995 added 7 commits September 18, 2025 12:31

Merge remote-tracking branch 'origin/develop' into feature_SST_IDDES

ff56f36

update meson and ninja

707afa4

Merge remote-tracking branch 'origin/develop' into HEAD

b249f2c

Removed SAS implementation (not working)

f10c465

- Removed debug quantities

37a866f

- Made Get/SetSRSGridSize non virtual

- Re-introduced the virtual function

ac2078c

- Fixed some notation

0c8d49a

- Used GeometryToolbox when possible

github-advanced-security bot found potential problems Oct 2, 2025

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rois1995 added 5 commits October 2, 2025 18:37

- Fix compilation issues

86db90b

- Fixed variable inputs

d4564da

- Fixed some thread sanitizer problems

177276a

- Removed unused functions

e260cc4

- Rearrenged and renamed outputs

- Fixed some notation

7e57afe

- Remove unused variables

- Added SST-EDDES formulation for unstructured grids

f193796

github-advanced-security bot found potential problems Oct 30, 2025

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Merge remote-tracking branch 'origin/develop' into feature_SST_IDDES

c5e1dee

		SAS_SIMPLE, /!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. /
		SAS_COMPLICATED, /!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. /

		SAS_TRAVIS, /!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. /
		SAS_BABU, /!< \brief Menter k-w SST model with Scale Adaptive Simulations modifications. /

	dk = Density_i * sqrt(ScalarVar_i[0]ScalarVar_i[0]ScalarVar_i[0]) / lengthScale_i;
	dk = Density_i * sqrt(pow(ScalarVar_i[0], 3)) / lengthScale_i;


		const su2double f_max = 1.0, f_min = 0.1, a1 = 0.15, a2 = 0.3;

		const auto nNeigh = geometry->nodes->GetnPoint(iPoint);

Implementation of DDES and SAS formulations for SST #2150

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Implementation of DDES and SAS formulations for SST #2150

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