From 41dacf83c654d216e43ca0e1ac548ea8d9904b78 Mon Sep 17 00:00:00 2001
From: Ian bell <ian.h.bell@gmail.com>
Date: Mon, 19 May 2014 22:39:04 +0200
Subject: [PATCH] HEOS can call transport properties

Signed-off-by: Ian bell <ian.h.bell@gmail.com>
---
 .../Helmholtz/HelmholtzEOSMixtureBackend.cpp  | 24 +++++++++++++++++++
 .../Helmholtz/HelmholtzEOSMixtureBackend.h    |  1 +
 2 files changed, 25 insertions(+)

diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
index a87dc12d..5b5af850 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.cpp
@@ -23,6 +23,7 @@
 #include "MatrixMath.h"
 #include "VLERoutines.h"
 #include "FlashRoutines.h"
+#include "TransportRoutines.h"
 
 namespace CoolProp {
 
@@ -127,6 +128,29 @@ long double HelmholtzEOSMixtureBackend::calc_surface_tension(void)
         throw NotImplementedError(format("surface tension not implemented for mixtures"));
     }
 }
+long double HelmholtzEOSMixtureBackend::calc_viscosity(void)
+{
+    if (is_pure_or_pseudopure)
+    {
+        // Dilute part
+        long double eta_dilute = TransportRoutines::dilute_gas_viscosity(*this);
+        
+        // Residual part
+        long double B_eta_initial = TransportRoutines::initial_density_dependence_viscosity_term(*this);
+        long double rho = rhomolar();
+        long double initial_part = eta_dilute*B_eta_initial*rhomolar();
+        long double delta_eta_h = TransportRoutines::modified_Batschinski_Hildebrand_viscosity_term(*this);
+        long double eta_residual = initial_part + delta_eta_h;
+
+        // Critical part
+        long double eta_critical = 0;
+        return eta_dilute + eta_residual + eta_critical;
+    }
+    else
+    {
+        throw NotImplementedError(format("viscosity not implemented for mixtures"));
+    }
+}
 long double HelmholtzEOSMixtureBackend::calc_Ttriple(void)
 {
     double summer = 0;
diff --git a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
index c03fbffe..4c9ec4f2 100644
--- a/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
+++ b/src/Backends/Helmholtz/HelmholtzEOSMixtureBackend.h
@@ -117,6 +117,7 @@ public:
     long double calc_d2alpha0_dTau2(void);
 
     long double calc_surface_tension(void);
+    long double calc_viscosity(void);
 
     long double calc_Tmax(void);
     long double calc_pmax(void);