[Thermo] Keep PureFluidPhase state data consistent

Previously, calls to setTemperature, setDensity, and setState_TR did not result
in the underlying Substance object being updated. In addition, the
isothermalCompressibility and thermalExpansionCoeff methods did not synchronize
the state.

Now, setting the state of the PureFluidPhase object always sets the state of the
Substance object, and no synchronization is required in property calculation
functions.

include/cantera/thermo/PureFluidPhase.h

@@ -68,6 +68,8 @@ public:
      * @param p  Pressure (Pa)
      */
     virtual void setPressure(doublereal p);
+    virtual void setTemperature(double T);
+    virtual void setDensity(double rho);
 
     virtual void getChemPotentials(doublereal* mu) const {
         mu[0] = gibbs_mole();
@@ -178,9 +180,6 @@ protected:
      */
     void Set(tpx::PropertyPair::type n, double x, double y) const;
 
-    //! Sets the state using a TPX::TV call
-    void setTPXState() const;
-
 private:
     //! Pointer to the underlying tpx object Substance that does the work
     mutable std::unique_ptr<tpx::Substance> m_sub;

interfaces/cython/cantera/test/test_purefluid.py

@@ -138,6 +138,11 @@ class TestPureFluid(utilities.CanteraTest):
         self.assertNear(ref.thermal_expansion_coeff,
                         self.water.thermal_expansion_coeff, 1e-5)
 
+    def test_thermal_expansion_coeff_TD(self):
+        for T in [440, 550, 660]:
+            self.water.TD = T, 0.1
+            self.assertNear(T * self.water.thermal_expansion_coeff, 1.0, 1e-2)
+
     def test_fd_properties_twophase(self):
         self.water.TX = 400, 0.1
         self.assertEqual(self.water.cp, np.inf)

src/thermo/PureFluidPhase.cpp

@@ -85,50 +85,55 @@ double PureFluidPhase::maxTemp(size_t k) const
 
 doublereal PureFluidPhase::enthalpy_mole() const
 {
-    setTPXState();
     return m_sub->h() * m_mw;
 }
 
 doublereal PureFluidPhase::intEnergy_mole() const
 {
-    setTPXState();
     return m_sub->u() * m_mw;
 }
 
 doublereal PureFluidPhase::entropy_mole() const
 {
-    setTPXState();
     return m_sub->s() * m_mw;
 }
 
 doublereal PureFluidPhase::gibbs_mole() const
 {
-    setTPXState();
     return m_sub->g() * m_mw;
 }
 
 doublereal PureFluidPhase::cp_mole() const
 {
-    setTPXState();
     return m_sub->cp() * m_mw;
 }
 
 doublereal PureFluidPhase::cv_mole() const
 {
-    setTPXState();
     return m_sub->cv() * m_mw;
 }
 
 doublereal PureFluidPhase::pressure() const
 {
-    setTPXState();
     return m_sub->P();
 }
 
 void PureFluidPhase::setPressure(doublereal p)
 {
     Set(tpx::PropertyPair::TP, temperature(), p);
-    setDensity(1.0/m_sub->v());
+    ThermoPhase::setDensity(1.0/m_sub->v());
+}
+
+void PureFluidPhase::setTemperature(double T)
+{
+    ThermoPhase::setTemperature(T);
+    Set(tpx::PropertyPair::TV, T, m_sub->v());
+}
+
+void PureFluidPhase::setDensity(double rho)
+{
+    ThermoPhase::setDensity(rho);
+    Set(tpx::PropertyPair::TV, m_sub->Temp(), 1.0/rho);
 }
 
 void PureFluidPhase::Set(tpx::PropertyPair::type n, double x, double y) const
@@ -136,11 +141,6 @@ void PureFluidPhase::Set(tpx::PropertyPair::type n, double x, double y) const
     m_sub->Set(n, x, y);
 }
 
-void PureFluidPhase::setTPXState() const
-{
-    Set(tpx::PropertyPair::TV, temperature(), 1.0/density());
-}
-
 doublereal PureFluidPhase::isothermalCompressibility() const
 {
     return m_sub->isothermalCompressibility();
@@ -356,24 +356,21 @@ doublereal PureFluidPhase::satPressure(doublereal t)
 
 doublereal PureFluidPhase::vaporFraction() const
 {
-    setTPXState();
     return m_sub->x();
 }
 
 void PureFluidPhase::setState_Tsat(doublereal t, doublereal x)
 {
-    setTemperature(t);
-    setTPXState();
     Set(tpx::PropertyPair::TX, t, x);
-    setDensity(1.0/m_sub->v());
+    ThermoPhase::setTemperature(t);
+    ThermoPhase::setDensity(1.0/m_sub->v());
 }
 
 void PureFluidPhase::setState_Psat(doublereal p, doublereal x)
 {
-    setTPXState();
     Set(tpx::PropertyPair::PX, p, x);
-    setTemperature(m_sub->Temp());
-    setDensity(1.0/m_sub->v());
+    ThermoPhase::setTemperature(m_sub->Temp());
+    ThermoPhase::setDensity(1.0/m_sub->v());
 }
 
 std::string PureFluidPhase::report(bool show_thermo, doublereal threshold) const