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pcarruscag merged 2 commits into from
Apr 17, 2026
Merged

Don't store/use secondary partial derivatives when it's not necessary #2789

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pcarruscag Apr 16, 2026
cbfda59
don't allocate/use secondary variables for ideal gas
pcarruscag Apr 17, 2026
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36 changes: 20 additions & 16 deletions SU2_CFD/include/solvers/CFVMFlowSolverBase.inl
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Original file line number Diff line number Diff line change
Expand Up @@ -451,6 +451,8 @@ void CFVMFlowSolverBase<V, R>::Viscous_Residual_impl(unsigned long iEdge, CGeome

const bool implicit = (config->GetKind_TimeIntScheme() == EULER_IMPLICIT);
const bool tkeNeeded = (config->GetKind_Turb_Model() == TURB_MODEL::SST);
const bool ideal_gas = (config->GetKind_FluidModel() == STANDARD_AIR) ||
(config->GetKind_FluidModel() == IDEAL_GAS);

CVariable* turbNodes = nullptr;
if (tkeNeeded) turbNodes = solver_container[TURB_SOL]->GetNodes();
Expand All @@ -469,10 +471,10 @@ void CFVMFlowSolverBase<V, R>::Viscous_Residual_impl(unsigned long iEdge, CGeome

numerics->SetPrimitive(nodes->GetPrimitive(iPoint),
nodes->GetPrimitive(jPoint));

numerics->SetSecondary(nodes->GetSecondary(iPoint),
nodes->GetSecondary(jPoint));

if (!ideal_gas) {
numerics->SetSecondary(nodes->GetSecondary(iPoint),
nodes->GetSecondary(jPoint));
}
/*--- Gradients. ---*/

numerics->SetPrimVarGradient(nodes->GetGradient_Primitive(iPoint),
Expand Down Expand Up @@ -1149,6 +1151,8 @@ void CFVMFlowSolverBase<V, FlowRegime>::BC_Sym_Plane(CGeometry* geometry, CSolve
SU2_ZONE_SCOPED

const bool implicit = (config->GetKind_TimeIntScheme() == EULER_IMPLICIT);
const bool ideal_gas = (config->GetKind_FluidModel() == STANDARD_AIR) ||
(config->GetKind_FluidModel() == IDEAL_GAS);
const auto iVel = prim_idx.Velocity();

/*--- Blazek chapter 8.:
Expand Down Expand Up @@ -1205,7 +1209,9 @@ void CFVMFlowSolverBase<V, FlowRegime>::BC_Sym_Plane(CGeometry* geometry, CSolve

/*--- Set Primitive and Secondary for numerics class. ---*/
conv_numerics->SetPrimitive(V_domain, V_reflected);
conv_numerics->SetSecondary(nodes->GetSecondary(iPoint), nodes->GetSecondary(iPoint));
if (!ideal_gas) {
conv_numerics->SetSecondary(nodes->GetSecondary(iPoint), nodes->GetSecondary(iPoint));
}

/*--- Compute the residual using an upwind scheme. ---*/
auto residual = conv_numerics->ComputeResidual(config);
Expand Down Expand Up @@ -1329,6 +1335,8 @@ void CFVMFlowSolverBase<V, FlowRegime>::BC_Fluid_Interface(CGeometry* geometry,
CConfig* config) {
SU2_ZONE_SCOPED

const bool ideal_gas = config->GetKind_FluidModel() == STANDARD_AIR || config->GetKind_FluidModel() == IDEAL_GAS;

unsigned long iVertex, jVertex, iPoint, Point_Normal = 0;
unsigned short iDim, iVar, jVar, iMarker, nDonorVertex;

Expand Down Expand Up @@ -1380,19 +1388,15 @@ void CFVMFlowSolverBase<V, FlowRegime>::BC_Fluid_Interface(CGeometry* geometry,

conv_numerics->SetPrimitive(PrimVar_i, PrimVar_j);

if (FlowRegime == ENUM_REGIME::COMPRESSIBLE) {
if (!(config->GetKind_FluidModel() == STANDARD_AIR || config->GetKind_FluidModel() == IDEAL_GAS)) {
auto Secondary_i = nodes->GetSecondary(iPoint);

P_static = PrimVar_j[nDim + 1];
rho_static = PrimVar_j[nDim + 2];
GetFluidModel()->SetTDState_Prho(P_static, rho_static);
if (FlowRegime == ENUM_REGIME::COMPRESSIBLE && !ideal_gas) {
P_static = PrimVar_j[nDim + 1];
rho_static = PrimVar_j[nDim + 2];
GetFluidModel()->SetTDState_Prho(P_static, rho_static);

Secondary_j[0] = GetFluidModel()->GetdPdrho_e();
Secondary_j[1] = GetFluidModel()->GetdPde_rho();
Secondary_j[0] = GetFluidModel()->GetdPdrho_e();
Secondary_j[1] = GetFluidModel()->GetdPde_rho();

conv_numerics->SetSecondary(Secondary_i, Secondary_j);
}
conv_numerics->SetSecondary(nodes->GetSecondary(iPoint), Secondary_j);
}

/*--- Set the normal vector ---*/
Expand Down
6 changes: 0 additions & 6 deletions SU2_CFD/include/solvers/CSolver.hpp
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Expand Up @@ -83,7 +83,6 @@ class CSolver {
nPrimVar, /*!< \brief Number of primitive variables of the problem. */
nPrimVarGrad, /*!< \brief Number of primitive variables of the problem in the gradient computation. */
nSecondaryVar, /*!< \brief Number of primitive variables of the problem. */
nSecondaryVarGrad, /*!< \brief Number of primitive variables of the problem in the gradient computation. */
nVarGrad, /*!< \brief Number of variables for deallocating the LS Cvector. */
nDim; /*!< \brief Number of dimensions of the problem. */
unsigned long nPoint; /*!< \brief Number of points of the computational grid. */
Expand Down Expand Up @@ -415,11 +414,6 @@ class CSolver {
*/
inline unsigned short GetnSecondaryVar(void) const { return nSecondaryVar; }

/*!
* \brief Get the number of variables of the problem.
*/
inline unsigned short GetnSecondaryVarGrad(void) const { return nSecondaryVarGrad; }

/*!
* \brief Get the number of variables of the problem.
*/
Expand Down
2 changes: 0 additions & 2 deletions SU2_CFD/include/variables/CVariable.hpp
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Expand Up @@ -103,14 +103,12 @@ class CVariable {

VectorType SolutionExtra_BGS_k; /*!< \brief Intermediate storage, enables cross term extraction as that is also pushed to Solution. */

protected:
unsigned long nPoint = 0; /*!< \brief Number of points in the domain. */
unsigned long nDim = 0; /*!< \brief Number of dimension of the problem. */
unsigned long nVar = 0; /*!< \brief Number of variables of the problem. */
unsigned long nPrimVar = 0; /*!< \brief Number of primitive variables. */
unsigned long nPrimVarGrad = 0; /*!< \brief Number of primitives for which a gradient is computed. */
unsigned long nSecondaryVar = 0; /*!< \brief Number of secondary variables. */
unsigned long nSecondaryVarGrad = 0; /*!< \brief Number of secondaries for which a gradient is computed. */
unsigned long nAuxVar = 0; /*!< \brief Number of auxiliary variables. */

/*--- Only allow default construction by derived classes. ---*/
Expand Down
25 changes: 16 additions & 9 deletions SU2_CFD/src/solvers/CEulerSolver.cpp
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Expand Up @@ -121,7 +121,6 @@ CEulerSolver::CEulerSolver(CGeometry *geometry, CConfig *config,
/*--- Centered schemes only need gradients for viscous fluxes (T and v). ---*/
nPrimVarGrad = EulerNPrimVarGrad(config, nDim);
nSecondaryVar = nSecVar;
nSecondaryVarGrad = 2;

/*--- Initialize nVarGrad for deallocation ---*/

Expand Down Expand Up @@ -1883,8 +1882,11 @@ void CEulerSolver::Upwind_Residual(CGeometry *geometry, CSolver **solver_contain

/*--- Get primitive and secondary variables ---*/

auto V_i = nodes->GetPrimitive(iPoint); auto V_j = nodes->GetPrimitive(jPoint);
auto S_i = nodes->GetSecondary(iPoint); auto S_j = nodes->GetSecondary(jPoint);
auto V_i = nodes->GetPrimitive(iPoint);
auto V_j = nodes->GetPrimitive(jPoint);

const su2double* S_i = ideal_gas? nullptr : nodes->GetSecondary(iPoint);
const su2double* S_j = ideal_gas? nullptr : nodes->GetSecondary(jPoint);

/*--- Set them with or without high order reconstruction using MUSCL strategy. ---*/

Expand Down Expand Up @@ -5081,9 +5083,11 @@ void CEulerSolver::BC_Riemann(CGeometry *geometry, CSolver **solver_container,

const string Marker_Tag = config->GetMarker_All_TagBound(val_marker);
const bool viscous = config->GetViscous(),
implicit = (config->GetKind_TimeIntScheme() == EULER_IMPLICIT),
implicit = config->GetKind_TimeIntScheme() == EULER_IMPLICIT,
gravity = config->GetGravityForce(),
tkeNeeded = (config->GetKind_Turb_Model() == TURB_MODEL::SST);
tkeNeeded = config->GetKind_Turb_Model() == TURB_MODEL::SST,
ideal_gas = config->GetKind_FluidModel() == STANDARD_AIR ||
config->GetKind_FluidModel() == IDEAL_GAS;

su2double **P_Tensor = new su2double*[nVar],
**invP_Tensor = new su2double*[nVar];
Expand Down Expand Up @@ -5451,7 +5455,7 @@ void CEulerSolver::BC_Riemann(CGeometry *geometry, CSolver **solver_container,

/*--- Secondary variables ---*/

auto S_domain = nodes->GetSecondary(iPoint);
const su2double* S_domain = ideal_gas? nullptr : nodes->GetSecondary(iPoint);

/*--- Compute secondary thermodynamic properties (partial derivatives...) ---*/
su2double S_boundary[8];
Expand Down Expand Up @@ -5527,6 +5531,8 @@ void CEulerSolver::BC_TurboRiemann(CGeometry *geometry, CSolver **solver_contain
bool viscous = config->GetViscous();
bool gravity = (config->GetGravityForce());
bool tkeNeeded = (config->GetKind_Turb_Model() == TURB_MODEL::SST);
const bool ideal_gas = config->GetKind_FluidModel() == STANDARD_AIR ||
config->GetKind_FluidModel() == IDEAL_GAS;

su2double *Normal, *turboNormal, *UnitNormal, *FlowDirMix, FlowDirMixMag, *turboVelocity;
Normal = new su2double[nDim];
Expand Down Expand Up @@ -5947,7 +5953,7 @@ void CEulerSolver::BC_TurboRiemann(CGeometry *geometry, CSolver **solver_contain

/*--- Secondary variables ---*/

S_domain = nodes->GetSecondary(iPoint);
S_domain = ideal_gas ? nullptr : nodes->GetSecondary(iPoint);

/*--- Compute secondary thermodynamic properties (partial derivatives...) ---*/

Expand Down Expand Up @@ -6203,6 +6209,8 @@ void CEulerSolver::BC_Giles(CGeometry *geometry, CSolver **solver_container, CNu
bool implicit = (config->GetKind_TimeIntScheme() == EULER_IMPLICIT);
string Marker_Tag = config->GetMarker_All_TagBound(val_marker);
bool viscous = config->GetViscous();
const bool ideal_gas = config->GetKind_FluidModel() == STANDARD_AIR ||
config->GetKind_FluidModel() == IDEAL_GAS;
unsigned short nSpanWiseSections = geometry->GetnSpanWiseSections(config->GetMarker_All_TurbomachineryFlag(val_marker));
su2double relfacAvgCfg = config->GetGiles_RelaxFactorAverage(Marker_Tag);
su2double relfacFouCfg = config->GetGiles_RelaxFactorFourier(Marker_Tag);
Expand Down Expand Up @@ -6538,8 +6546,7 @@ void CEulerSolver::BC_Giles(CGeometry *geometry, CSolver **solver_container, CNu
V_domain = nodes->GetPrimitive(iPoint);

/*--- Retrieve domain Secondary variables ---*/
S_domain = nodes->GetSecondary(iPoint);

S_domain = ideal_gas? nullptr : nodes->GetSecondary(iPoint);

/*--- Compute the internal state u_i ---*/
Velocity2_i = 0;
Expand Down
5 changes: 3 additions & 2 deletions SU2_CFD/src/solvers/CNSSolver.cpp
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Expand Up @@ -158,8 +158,9 @@ unsigned long CNSSolver::SetPrimitive_Variables(CSolver **solver_container, cons

/*--- Compressible flow, primitive variables nDim+5, (T, vx, vy, vz, P, rho, h, c, lamMu, eddyMu, ThCond, Cp) ---*/

bool physical = static_cast<CNSVariable*>(nodes)->SetPrimVar(iPoint, eddy_visc, turb_ke, GetFluidModel());
nodes->SetSecondaryVar(iPoint, GetFluidModel());
auto* ns_nodes = static_cast<CNSVariable*>(nodes);
bool physical = ns_nodes->SetPrimVar(iPoint, eddy_visc, turb_ke, GetFluidModel());
ns_nodes->SetSecondaryVar(iPoint, GetFluidModel());

/*--- Check for non-realizable states for reporting. ---*/

Expand Down
17 changes: 12 additions & 5 deletions SU2_CFD/src/variables/CEulerVariable.cpp
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Expand Up @@ -43,6 +43,13 @@ unsigned long EulerNPrimVarGrad(const CConfig *config, unsigned long ndim) {
return ndim + 4;
}

unsigned long EulerNSecVar(const CConfig *config) {
const bool ideal_gas = config->GetKind_FluidModel() == STANDARD_AIR ||
config->GetKind_FluidModel() == IDEAL_GAS;
if (ideal_gas) return 0;
return config->GetViscous() ? 8 : 2;
}

CEulerVariable::CEulerVariable(su2double density, const su2double *velocity, su2double energy, unsigned long npoint,
unsigned long ndim, unsigned long nvar, const CConfig *config)
: CFlowVariable(npoint, ndim, nvar, ndim + 9, EulerNPrimVarGrad(config, ndim), config),
Expand All @@ -52,8 +59,7 @@ CEulerVariable::CEulerVariable(su2double density, const su2double *velocity, su2
(config->GetTime_Marching() == TIME_MARCHING::DT_STEPPING_2ND);
const bool classical_rk4 = (config->GetKind_TimeIntScheme_Flow() == CLASSICAL_RK4_EXPLICIT);

nSecondaryVar = config->GetViscous() ? 8 : 2,
nSecondaryVarGrad = 2;
nSecondaryVar = EulerNSecVar(config);

/*--- Solution initialization ---*/

Expand Down Expand Up @@ -156,10 +162,11 @@ bool CEulerVariable::SetPrimVar(unsigned long iPoint, CFluidModel *FluidModel) {
}

void CEulerVariable::SetSecondaryVar(unsigned long iPoint, CFluidModel *FluidModel) {
if (nSecondaryVar == 0) return;

/*--- Compute secondary thermo-physical properties (partial derivatives...) ---*/
/*--- Compute secondary thermo-physical properties (partial derivatives...) ---*/

SetdPdrho_e(iPoint, FluidModel->GetdPdrho_e());
SetdPde_rho(iPoint, FluidModel->GetdPde_rho());
SetdPdrho_e(iPoint, FluidModel->GetdPdrho_e());
SetdPde_rho(iPoint, FluidModel->GetdPde_rho());

}
21 changes: 11 additions & 10 deletions SU2_CFD/src/variables/CNSVariable.cpp
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Expand Up @@ -210,21 +210,22 @@ bool CNSVariable::SetPrimVar(unsigned long iPoint, su2double eddy_visc, su2doubl
}

void CNSVariable::SetSecondaryVar(unsigned long iPoint, CFluidModel *FluidModel) {
if (nSecondaryVar == 0) return;

/*--- Compute secondary thermodynamic properties (partial derivatives...) ---*/
/*--- Compute secondary thermodynamic properties (partial derivatives...) ---*/

SetdPdrho_e( iPoint, FluidModel->GetdPdrho_e() );
SetdPde_rho( iPoint, FluidModel->GetdPde_rho() );
SetdPdrho_e( iPoint, FluidModel->GetdPdrho_e() );
SetdPde_rho( iPoint, FluidModel->GetdPde_rho() );

SetdTdrho_e( iPoint, FluidModel->GetdTdrho_e() );
SetdTde_rho( iPoint, FluidModel->GetdTde_rho() );
SetdTdrho_e( iPoint, FluidModel->GetdTdrho_e() );
SetdTde_rho( iPoint, FluidModel->GetdTde_rho() );

/*--- Compute secondary thermo-physical properties (partial derivatives...) ---*/
/*--- Compute secondary thermo-physical properties (partial derivatives...) ---*/

Setdmudrho_T( iPoint, FluidModel->Getdmudrho_T() );
SetdmudT_rho( iPoint, FluidModel->GetdmudT_rho() );
Setdmudrho_T( iPoint, FluidModel->Getdmudrho_T() );
SetdmudT_rho( iPoint, FluidModel->GetdmudT_rho() );

Setdktdrho_T( iPoint, FluidModel->Getdktdrho_T() );
SetdktdT_rho( iPoint, FluidModel->GetdktdT_rho() );
Setdktdrho_T( iPoint, FluidModel->Getdktdrho_T() );
SetdktdT_rho( iPoint, FluidModel->GetdktdT_rho() );

}
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