[PL] H2,rho; Remove unused getDerivGasDensity().

ProcessLib/TwoPhaseFlowWithPrho/TwoPhaseFlowWithPrhoMaterialProperties.cpp

@@ -98,16 +98,6 @@ double TwoPhaseFlowWithPrhoMaterialProperties::getGasDensity(
     return _gas_density->getValue(vars);
 }
 
-double TwoPhaseFlowWithPrhoMaterialProperties::getDerivGasDensity(
-    const double p, const double T) const
-{
-    ArrayType vars;
-    vars[static_cast<int>(MaterialLib::Fluid::PropertyVariableType::T)] = T;
-    vars[static_cast<int>(MaterialLib::Fluid::PropertyVariableType::p)] = p;
-
-    return _gas_density->getdValue(vars,
-                                   MaterialLib::Fluid::PropertyVariableType::p);
-}
 double TwoPhaseFlowWithPrhoMaterialProperties::getLiquidViscosity(
     const double p, const double T) const
 {

ProcessLib/TwoPhaseFlowWithPrho/TwoPhaseFlowWithPrhoMaterialProperties.h

@@ -89,7 +89,6 @@ public:
     double getGasDensity(const double p, const double T) const;
     double getGasViscosity(const double p, const double T) const;
     double getLiquidViscosity(const double p, const double T) const;
-    double getDerivGasDensity(double const p, double const T) const;
     bool computeConstitutiveRelation(
         double const t,
         ParameterLib::SpatialPosition const& x_position,