Add local timestep + CFL as volume output by j-signorelli · Pull Request #2060 · su2code/SU2
Oh interesting, just to be fully complete here's what made me think that:
1.I have a well-converged steady-state solution and outputted the minimum DT's for each cell when running with a CFL=1.0, no adaptive. I was unable to restart this for an unsteady one with no changes in BCs without using a DT orders-of-magnitude smaller.
-
When I run /Tutorials/compressible_flow/Turbulent_OneraM6 with
MIN_DELTA_TIMEset as a screen output, I get orders-of-magnitude different final timestep when I run withREF_DIMENSIONALIZATION= DIMENSIONALinstead ofFREESTREAM_VEL_EQ_ONE. -
When I run
SU2_CFD -don the /Tutorials/compressible_flow/Unsteady_NACA0012 example usingFREESTREAM_VEL_EQ_ONEI see the attached image below, which appears to nondimensionalize using length/velocity.
- I also looked briefly at the code it appeared that the calculations were using nondimensional values; here's what I looked at:
Setting of local timestep:
| if (Vol != 0.0) { | |
| su2double Local_Delta_Time = nodes->GetLocalCFL(iPoint)*Vol / nodes->GetMax_Lambda_Inv(iPoint); | |
| if(viscous) { | |
| su2double dt_visc = nodes->GetLocalCFL(iPoint)*K_v*Vol*Vol / nodes->GetMax_Lambda_Visc(iPoint); | |
| Local_Delta_Time = min(Local_Delta_Time, dt_visc); | |
| } | |
| minDt = min(minDt, Local_Delta_Time); | |
| maxDt = max(maxDt, Local_Delta_Time); | |
| nodes->SetDelta_Time(iPoint, min(Local_Delta_Time, config->GetMax_DeltaTime())); | |
| } | |
| else { | |
| nodes->SetDelta_Time(iPoint,0.0); | |
| } | |
| } |
Calculation of Lambda's:
| auto jPoint = geometry->nodes->GetPoint(iPoint,iNeigh); | |
| auto iEdge = geometry->nodes->GetEdge(iPoint,iNeigh); | |
| auto Normal = geometry->edges->GetNormal(iEdge); | |
| auto Area2 = GeometryToolbox::SquaredNorm(nDim, Normal); | |
| /*--- Mean Values ---*/ | |
| su2double Mean_ProjVel = 0.5 * (nodes->GetProjVel(iPoint,Normal) + nodes->GetProjVel(jPoint,Normal)); | |
| su2double Mean_SoundSpeed = soundSpeed(*nodes, iPoint, jPoint) * sqrt(Area2); | |
| /*--- Adjustment for grid movement ---*/ | |
| if (dynamic_grid) { | |
| const su2double *GridVel_i = geometry->nodes->GetGridVel(iPoint); | |
| const su2double *GridVel_j = geometry->nodes->GetGridVel(jPoint); | |
| for (unsigned short iDim = 0; iDim < nDim; iDim++) | |
| Mean_ProjVel -= 0.5 * (GridVel_i[iDim] + GridVel_j[iDim]) * Normal[iDim]; | |
| } | |
| /*--- Inviscid contribution ---*/ | |
| su2double Lambda = fabs(Mean_ProjVel) + Mean_SoundSpeed; | |
| nodes->AddMax_Lambda_Inv(iPoint,Lambda); | |
| /*--- Viscous contribution ---*/ | |
| if (!viscous) continue; | |
| Lambda = lambdaVisc(*nodes, iPoint, jPoint) * Area2; | |
| nodes->AddMax_Lambda_Visc(iPoint, Lambda); |
GetProjVel:
| /*! | |
| * \brief Get the projected velocity in a unitary vector direction (compressible solver). | |
| * \param[in] val_vector - Direction of projection. | |
| * \return Value of the projected velocity. | |
| */ | |
| inline su2double GetProjVel(unsigned long iPoint, const su2double *val_vector) const final { | |
| su2double ProjVel = 0.0; | |
| for (unsigned long iDim = 0; iDim < nDim; iDim++) | |
| ProjVel += Primitive(iPoint,iDim+indices.Velocity())*val_vector[iDim]; | |
| return ProjVel; | |
| } |
Then at this point admittedly I just assumed that the MatrixType Primitive of CEulerVariable was indeed nondimensional. I am not familiar with where/when data is stored/updated throughout SU2 as nondimensional v dimensional.