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

+    switch(kind_hybridRANSLES){
+      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);
+
+        nodes->SetDebug_Quantities(config, iPoint, f_d, l_RANS, l_LES, r_d);
+
+        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;
+
+        nodes->SetDebug_Quantities(config, iPoint, ftilda_d, l_RANS, l_LES, r_dl, r_dt);
+
+        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 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 Delta = min(C_w * max(sqrt(wallDist2), h_max), h_max);
+        const su2double l_LES = C_DES * Delta;
+
+        nodes->SetDebug_Quantities(config, iPoint, ftilda_d, l_RANS, l_LES, r_dt);
+
+        DES_lengthScale = ftilda_d*l_RANS + (1.0 - ftilda_d) * l_LES;
+
+        break;
+      }
+    }


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

@@ -190,6 +190,10 @@ class CNumerics {

  bool bounded_scalar = false;    /*!< \brief Flag for bounded scalar problem */

+  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 · 2025-03-17T16:38:43Z

Ok but why should I do that? I have periodic boundaries here.

pcarruscag · 2025-03-17T16:43:21Z

You mentioned problems at the periodic boundaries

I have tried with the Roe and the L2Roe scheme but neither of them worked as I had problems at the periodic boundaries.

rois1995 · 2025-03-26T18:54:24Z

In the end the problem was just that the simulation was not converged. Once it got to convergence then the problem disappeared. In the end, I opted for the JST scheme as it should be less dissipative than the Roe+MUSCL one and is recommended for DDES simulations.

News on NACA0021 case:

I have run the SA-EDDES, SST-DDES, SST-IDDES, SST-SIDDES, SST-EDDES models on the coarse mesh of the paper from Molina et al. .

Coefficients are averaged on the last 100 CUs.

Case	SA-EDDES	SST-DDES	SST-IDDES	SST-SIDDES	SST-EDDES	Exp.
mean $C_L$	1.01091	0.95931	1.05284	0.96727	1.04936	0.931
mean $C_D$	1.68240	1.60561	1.74839	1.63322	1.75828	1.517

Pressure Coefficients distribution

FFTs of lift and drag coefficients

I had to divide them for clarity.

It seems that the EDDES implementation for SST is similar to the SA one in the results, although a little bit less accurate. If someone would like to perform a finer mesh I will be glad to provide configs and grids.

SST-DDES is mid-way between SST-IDDES and SST-SIDDES. Actually, SIDDES is the Simplified IDDES version, thus I guess it is expected to perform close to the IDDES (also seen in the reference paper). The second $c_L$ peak is not really captured by any method. Overall, good agreement between all of the DDES simulations. Further mesh refinement is needed though.

I have also some results on the Backward Facing Step case that I will post in the next days.

rois1995 · 2025-03-26T19:06:23Z

I am actually quite unsure of the implementation of the EDDES for SA. I think that the correct implementation is the one that I have used in the SST model (they are equivalent).

SA Implementation

su2double ln_max = 0.0;
for (const auto jPoint : geometry->nodes->GetPoints(iPoint)) {
  const auto coord_j = geometry->nodes->GetCoord(jPoint);
  su2double delta[MAXNDIM] = {};
  for (auto iDim = 0u; iDim < nDim; iDim++){
    delta[iDim] = fabs(coord_j[iDim] - coord_i[iDim]);
  }
  su2double ln[3];
  ln[0] = delta[1]*ratioOmega[2] - delta[2]*ratioOmega[1];
  ln[1] = delta[2]*ratioOmega[0] - delta[0]*ratioOmega[2];
  ln[2] = delta[0]*ratioOmega[1] - delta[1]*ratioOmega[0];
  const su2double aux_ln = sqrt(ln[0]*ln[0] + ln[1]*ln[1] + ln[2]*ln[2]);
  ln_max = max(ln_max, aux_ln);
  vortexTiltingMeasure += nodes->GetVortex_Tilting(jPoint);
}
vortexTiltingMeasure /= (nNeigh + 1);

SST Implementation

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] = {};
    // This should only be performed on 3D cases anyway
    for (auto iDim = 0u; iDim < 3; iDim++){
      delta[iDim] = (coord_j[iDim] - coord_k[iDim])/2.0; // Should I divide by 2 as I am interested in the dual volume?
    }
    su2double l_n_minus_m[3];
    GeometryToolbox::CrossProduct(delta, vorticityDir, l_n_minus_m);
    deltaOmega = max(deltaOmega, GeometryToolbox::Norm(nDim, l_n_minus_m));
  }

  // Add to VTM(iPoint) to perform the average
  vortexTiltingMeasure += nodes->GetVortex_Tilting(jPoint);
}
deltaOmega /= (1/sqrt(3));
vortexTiltingMeasure /= (nNeigh+1);

Proposed here

rois1995 · 2025-03-26T19:31:36Z

Backward Facing Step

The test case is the one in the NASA TMR page.

$Re_H = 36000$
$Ma = 0.128$
$T_\infty= 537 \text{R}$

The grid is taken from the Level 3 among the 2D CGNS grids given here. Then it has been extended in the spanwise direction for 4H and with 40 points. The timestep is $\Delta t = 0.02 H / U_\infty$, the total simulation time is $t_{tot} = 300 H/U_\infty$ and the results have been averaged on the last 270 CUs. The JST scheme has been used.

Velocity profiles in the channel

The SST-DDES model is lacking accuracy across all the velocity profiles, not really clear why since the results for the NACA0021 airfoil were satisfactory. The SST-EDDES and SA-EDDES solutions are similar, but the SST implementation is even better when the velocity fluctuations are considered.

Reynolds stresses in the channel

Reference from here:

Results:

The Reynolds stresses are consistent between the SA-EDDES and SST-EDDES formulations and are quite in line with the reference solutions (although they have used a finer grid). The SST-DDES results are the ones that deviates a lot, as also seen in the velocity profiles above.

rois1995 · 2025-03-31T08:14:10Z

BFS Update

I have done the simulations with the SST-IDDES and SST-SIDDES also for the coarse mesh of the BFS case. Results are quite good compared to SST-EDDES simulations. Only the SST-DDES case seems to have the worst results among all of them.

Velocity Profiles in the channel

Reynolds Stresses

I am currently running the Medium grid only for the SST-EDDES case, but it will take a long time before having meaningful results.

Up to know I haven't found a way of making the SAS model to work. There is something wrong with the computation of the Von-Karman length scale, which can be directly related to a wrong computation of the laplacian of the velocity. If anyone is interested in investigating this I think it will be material for another PR.

I will remove the WIP from this PR.

SU2_CFD/src/solvers/CTurbSASolver.cpp

        const su2double r_d = (kinematicViscosityTurb+kinematicViscosity)/(uijuij*k2*pow(wallDistance, 2.0));
        const su2double f_d = 1.0-tanh(pow(8.0*r_d,3.0));

        const su2double distDES = constDES * maxDelta;
        lengthScale = wallDistance-f_d*max(0.0,(wallDistance-distDES));

        break;
      }
      case SA_ZDES: {
        /*--- Recent improvements in the Zonal Detached Eddy Simulation (ZDES) formulation.
         Deck
         Theoretical and Computational Fluid Dynamics - 2012
         ---*/

        const su2double deltaDDES = geometry->nodes->GetMaxLength(iPoint);

        su2double delta[MAXNDIM] = {}, ratioOmega[MAXNDIM] = {};

        for (const auto jPoint : geometry->nodes->GetPoints(iPoint)) {
          const auto coord_j = geometry->nodes->GetCoord(jPoint);
          for (auto iDim = 0u; iDim < nDim; iDim++){
            const su2double deltaAux = abs(coord_j[iDim] - coord_i[iDim]);
            delta[iDim] = max(delta[iDim], deltaAux);
          }
        }

        const su2double omega = GeometryToolbox::Norm(3, vorticity);

        for (auto iDim = 0u; iDim < 3; iDim++){
          ratioOmega[iDim] = vorticity[iDim]/omega;
        }

        su2double maxDelta = sqrt(pow(ratioOmega[0], 2)*delta[1]*delta[2] +
                                  pow(ratioOmega[1], 2)*delta[0]*delta[2] +
                                  pow(ratioOmega[2], 2)*delta[0]*delta[1]);

        const su2double r_d = (kinematicViscosityTurb+kinematicViscosity)/(uijuij*k2*pow(wallDistance, 2.0));
        const su2double f_d = 1.0-tanh(pow(8.0*r_d,3.0));

        if (f_d < 0.99){
          maxDelta = deltaDDES;
        }

        const su2double distDES = constDES * maxDelta;
        lengthScale = wallDistance-f_d*max(0.0,(wallDistance-distDES));

        break;
      }
      case SA_EDDES: {
        /*--- An Enhanced Version of DES with Rapid Transition from RANS to LES in Separated Flows.
         Shur et al.
         Flow Turbulence Combust - 2015
         ---*/

        su2double vortexTiltingMeasure = nodes->GetVortex_Tilting(iPoint);

        const su2double omega = GeometryToolbox::Norm(3, vorticity);

        su2double ratioOmega[MAXNDIM] = {};

        for (auto iDim = 0; iDim < 3; iDim++){
          ratioOmega[iDim] = vorticity[iDim]/omega;
        }

        const su2double deltaDDES = geometry->nodes->GetMaxLength(iPoint);

        su2double ln_max = 0.0;
        for (const auto jPoint : geometry->nodes->GetPoints(iPoint)) {
          const auto coord_j = geometry->nodes->GetCoord(jPoint);
          su2double delta[MAXNDIM] = {};
          for (auto iDim = 0u; iDim < nDim; iDim++){
            delta[iDim] = fabs(coord_j[iDim] - coord_i[iDim]);
          }
          su2double ln[3];
          ln[0] = delta[1]*ratioOmega[2] - delta[2]*ratioOmega[1];
          ln[1] = delta[2]*ratioOmega[0] - delta[0]*ratioOmega[2];
          ln[2] = delta[0]*ratioOmega[1] - delta[1]*ratioOmega[0];
          const su2double aux_ln = sqrt(ln[0]*ln[0] + ln[1]*ln[1] + ln[2]*ln[2]);
          ln_max = max(ln_max, aux_ln);
          vortexTiltingMeasure += nodes->GetVortex_Tilting(jPoint);
        }
        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 = (kinematicViscosityTurb+kinematicViscosity)/(uijuij*k2*pow(wallDistance, 2.0));
        const su2double f_d = 1.0-tanh(pow(8.0*r_d,3.0));

        su2double maxDelta = (ln_max/sqrt(3.0)) * f_kh;
        if (f_d < 0.999){
          maxDelta = deltaDDES;
        }

        const su2double distDES = constDES * maxDelta;
        lengthScale = wallDistance-f_d*max(0.0,(wallDistance-distDES));

+        break;
+      }


rois1995 · 2025-04-01T12:17:29Z

I've found a bug in SST-EDDES formulation, solved it but for some reason every simulation is now diverging, even the ones with SST-DDES. I will look into it.

EDIT: It seems to be related to #2484

EDIT: It was related to the restart file being computed without the fix, thus values of Omega near wall were wrong.

rois1995 · 2025-04-08T13:35:55Z

Backward Facing Step

I have re-run the SST-DDES and SST-EDDES simulations with the bug fixed from #2484 and a minor bug solved for SST-EDDES.

The fix seems to be slightly improving results for SST-DDES and worsening the results for SST-EDDES. However, what is happening for the EDDES model is that it is much more aligned with the SA-EDDES results with the fix included, which I think is desired as the LES formulation is essentially the same.

I have also tried changing the computation of the vorticity-aligned cell surface for the SA-EDDES model as it is supposed to be implemented (formulation shown in previous comments). The results are not much different for the BFS case but I think that the new (correct) formulation should be preferred.

I will try some more with the SAS formulation, if nothing works then I'll remove it from this PR.

bigfooted · 2025-04-09T06:42:17Z

are there simulation results from other codes for this case available for comparison? So we know if the current performance is as good as it gets or not?

rois1995 · 2025-04-09T12:27:29Z

The same case have been simulated by Molina et al. in the reference paper for the implementation of DDES in SU2. However, when I try to run the SA-EDDES model with Roe and FD as low dissipation it diverges (I am using the same grid as in the paper). I cannot find the specific config file that was used, thus I don't know if I am doing something wrong with the setup. The JST results are somewhat comparable with their, although I have a much larger simulation time (300H/U instead of 30). I will try making the Roe simulation work.

EDIT:

I have oscillations at the periodic boundaries when I use the FD low-dissipation method.

Pressure and Roe dissipation on the periodic boundary

Pressure and Roe dissipation at the center

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.

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

View reviewed changes

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

View reviewed changes

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

View reviewed changes

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

rois1995 added 6 commits March 18, 2025 16:15

- Added SLA DDES formulation to SST

d037e59

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

d9f329e

- compilation erorr

0adcb7e

- Fix memory leak

d50b123

- fixed formatting error

34a0271

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

04dfcd3

rois1995 added 3 commits March 28, 2025 19:17

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

a60fb13

- update externals

95ccc73

- update externals and subprojects

de45d5f

rois1995 changed the title ~~[WIP] Implementation of DDES and SAS formulations for SST~~ Implementation of DDES and SAS formulations for SST Mar 31, 2025

- Try changes to SA-EDDES

d172607

github-advanced-security bot found potential problems Mar 31, 2025

View reviewed changes

rois1995 added 4 commits April 1, 2025 12:34

- Fix bug in SST-EDDES

e5a916c

- Set debug quantities

c723a13

- try fix

d051f0b

- Fix output

c840256

rois1995 changed the title ~~Implementation of DDES and SAS formulations for SST~~ [WIP] Implementation of DDES and SAS formulations for SST Apr 1, 2025

- Fix output

9b997d7

rois1995 changed the title ~~[WIP] Implementation of DDES and SAS formulations for SST~~ Implementation of DDES and SAS formulations for SST Apr 8, 2025

		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. /

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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