1 files changed, 76 insertions, 0 deletions
diff --git a/Utilib/src/viscosity.c b/Utilib/src/viscosity.c
new file mode 100644
index 0000000..1b3f578
--- /dev/null
+++ b/Utilib/src/viscosity.c
@@ -0,0 +1,76 @@
+/*
+ freesteam - IAPWS-IF97 steam tables library
+ Copyright (C) 2004-2009  John Pye
+ 
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License
+ as published by the Free Software Foundation; either version 2
+ of the License, or (at your option) any later version.
+ 
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+ 
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+/*
+ Based on IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance
+ */
+
+#define FREESTEAM_BUILDING_LIB
+#include "viscosity.h"
+
+static double mu0(double tau);
+static double mu1(double del, double tau);
+
+#define VISCOSITY_MUSTAR 1.0e-6 /* Pa-s */
+
+#include <math.h>
+
+static double mu0(double tau){
+    const double H[4] = {1.67752, 2.20462, 0.6366564, -0.241605};
+    int i;
+    double sum = 0;
+    for (i = 0; i < 4; i++){
+        sum += H[i] * ipow(tau, i) ;
+    }
+    return 100.0 / (sqrt(tau) * sum);
+}
+
+
+
+static double mu1(double del, double tau){
+    const double H[6][7] = {
+        { 5.20094E-1, 2.22531E-1, -2.81378E-1, 1.61913E-1, -3.25372E-2, 0.0,         0.0},
+        { 8.50895E-2, 9.99115E-1, -9.06851E-1, 2.57399E-1,  0.0,        0.0,         0.0},
+        {-1.08374,    1.88797,    -7.72479E-1, 0.0,         0.0,        0.0,         0.0},
+        {-2.89555E-1, 1.26613,    -4.89837E-1, 0.0,         6.98452E-2, 0.0,        -4.35673E-3},
+        { 0.0,        0.0,        -2.57040E-1, 0.0,         0.0,        8.72102E-3,  0.0},
+        { 0.0,        1.20573E-1,  0.0,        0.0,         0.0,        0.0,        -5.93264E-4}
+    };
+	
+    int i, j;
+    double sum = 0;
+    double tau1 = 0;
+    for (i = 0; i < 6; i++){
+		tau1 = ipow(tau - 1, i);
+        for (j = 0; j < 7; j++){
+			if(0==H[i][j])continue;
+            sum += H[i][j] * tau1 * ipow(del - 1, j);
+        }
+    }
+    return exp(del * sum);
+}
+
+double freesteam_mu_rhoT(double rho, double T){
+	double del = rho / IAPWS97_RHOCRIT;
+	double tau = IAPWS97_TCRIT / T;
+
+        const int mu2 = 1;
+        /* critical enhancement to viscosity not implemented for IF-97, set to 1 */
+	return VISCOSITY_MUSTAR * mu0(tau) * mu1(del,tau) * mu2;
+}