ENH: liquidMixturePropertues - contribution by dkxls

- replaced TMax() function by pvInvert(X)
- added pseudo triple point temperature function

src/thermophysicalModels/properties/liquidMixtureProperties/liquidMixtureProperties/liquidMixtureProperties.C

@@ -103,12 +103,62 @@ Foam::scalar Foam::liquidMixtureProperties::Tc(const scalarField& x) const
 }
 
 
-Foam::scalar Foam::liquidMixtureProperties::TMax(const scalar p) const
+Foam::scalar Foam::liquidMixtureProperties::Tpt(const scalarField& x) const
 {
-    scalar T = -GREAT;
+    scalar Tpt = 0.0;
     forAll(properties_, i)
     {
-        T = max(T, properties_[i].pvInvert(p));
+        Tpt += x[i]*properties_[i].Tt();
+    }
+
+    return Tpt;
+}
+
+
+Foam::scalar Foam::liquidMixtureProperties::pvInvert
+(
+    const scalar p,
+    const scalarField& x
+) const
+{
+    // Set upper and lower bounds
+    scalar Thi = Tc(x);
+    scalar Tlo = Tpt(x);
+
+    // Check for critical and solid phase conditions
+    if (p >= pv(p, Thi, x))
+    {
+        return Thi;
+    }
+    else if (p < pv(p, Tlo, x))
+    {
+        WarningIn
+        (
+            "Foam::scalar Foam::liquidMixtureProperties::pvInvert"
+            "("
+            "    const scalar,"
+            "    const scalarField&"
+            ") const"
+        )   << "Pressure below triple point pressure: "
+            << "p = " << p << " < Pt = " << pv(p, Tlo, x) <<  nl << endl;
+        return -1;
+    }
+
+    // Set initial guess
+    scalar T = (Thi + Tlo)*0.5;
+
+    while ((Thi - Tlo) > 1.0e-4)
+    {
+        if ((pv(p, T, x) - p) <= 0.0)
+        {
+            Tlo = T;
+        }
+        else
+        {
+            Thi = T;
+        }
+
+        T = (Thi + Tlo)*0.5;
     }
 
     return T;

src/thermophysicalModels/properties/liquidMixtureProperties/liquidMixtureProperties/liquidMixtureProperties.H

@@ -141,8 +141,9 @@ public:
         //- Calculate the critical temperature of mixture
         scalar Tc(const scalarField& x) const;
 
-        //- Calculate the maximum temperature of mixture at given pressure
-        scalar TMax(const scalar p) const;
+        //- Invert the vapour pressure relationship to retrieve the boiling
+        //  temperature of the mixture as a function of pressure
+        scalar pvInvert(const scalar p, const scalarField& x) const;
 
         //- Return pseudocritical temperature according to Kay's rule
         scalar Tpc(const scalarField& x) const;
@@ -150,6 +151,9 @@ public:
         //- Return pseudocritical pressure (modified Prausnitz and Gunn)
         scalar Ppc(const scalarField& x) const;
 
+        //- Return pseudo triple point temperature (mole averaged formulation)
+        scalar Tpt(const scalarField& x) const;
+
         //- Return mixture accentric factor
         scalar omega(const scalarField& x) const;