From 707ee4799a11aeca59eabaf1b44ccab9d4e1680b Mon Sep 17 00:00:00 2001
From: Ian Bell <ian.h.bell@gmail.com>
Date: Thu, 4 Dec 2014 11:43:44 -0500
Subject: [PATCH] Brought back surface tension support

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
---
 src/AbstractState.cpp                                |  2 ++
 .../Helmholtz/HelmholtzEOSMixtureBackend.cpp         | 12 ++++++++++++
 src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h  |  3 ++-
 src/DataStructures.cpp                               |  1 +
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/AbstractState.cpp b/src/AbstractState.cpp
index 8e8064ef..01b4ae24 100644
--- a/src/AbstractState.cpp
+++ b/src/AbstractState.cpp
@@ -279,6 +279,8 @@ double AbstractState::keyed_output(int key)
         return viscosity();
     case iconductivity:
         return conductivity();
+	case isurface_tension:
+		return surface_tension();
     case iPhase:
         return phase();
     case iZ:
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
index 0774079d..2d42d1ba 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
@@ -271,6 +271,9 @@ long double HelmholtzEOSMixtureBackend::calc_saturation_ancillary(parameters par
                     return components[0]->ancillaries.rhoV.invert(value);
             }
         }
+		else if (param == isurface_tension && given == iT){
+			return components[0]->ancillaries.surface_tension.evaluate(value);
+		}
         else{
             throw ValueError(format("calc of %s given %s is invalid in calc_saturation_ancillary", 
                                     get_parameter_information(param,"short").c_str(), 
@@ -296,6 +299,15 @@ long double HelmholtzEOSMixtureBackend::calc_melting_line(int param, int given,
         throw NotImplementedError(format("calc_melting_line not implemented for mixtures"));
     }
 }
+long double HelmholtzEOSMixtureBackend::calc_surface_tension(void)
+{
+    if (is_pure_or_pseudopure){
+		return components[0]->ancillaries.surface_tension.evaluate(T());
+    }
+    else{
+        throw NotImplementedError(format("surface tension not implemented for mixtures"));
+    }
+}
 long double HelmholtzEOSMixtureBackend::calc_viscosity_dilute(void)
 {
     if (is_pure_or_pseudopure)
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
index c876821f..cabc28bc 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
@@ -195,7 +195,7 @@ public:
     long double calc_d3alpha0_dDelta_dTau2(void);
     long double calc_d3alpha0_dTau3(void);
 
-    //long double calc_surface_tension(void);
+    long double calc_surface_tension(void);
     long double calc_viscosity(void);
     long double calc_viscosity_dilute(void);
     long double calc_viscosity_background(void);
@@ -203,6 +203,7 @@ public:
     long double calc_conductivity(void);
     long double calc_conductivity_background(void);
 
+
     long double calc_Tmin(void);
     long double calc_Tmax(void);
     long double calc_pmax(void);
diff --git a/src/DataStructures.cpp b/src/DataStructures.cpp
index 83c192cd..ed636e94 100644
--- a/src/DataStructures.cpp
+++ b/src/DataStructures.cpp
@@ -135,6 +135,7 @@ public:
         index_map.insert(std::pair<std::string, int>("molemass", imolar_mass));
         index_map.insert(std::pair<std::string, int>("molarmass", imolar_mass));
         index_map.insert(std::pair<std::string, int>("A", ispeed_sound));
+		index_map.insert(std::pair<std::string, int>("I", isurface_tension));
 
         std::map<std::string,int>::iterator it;
         for(it = index_map.begin(); it != index_map.end(); ++it )