KTAmod update for higher temperatures (#1300)

equinor · Mar 7, 2025 · 7c193c5 · 7c193c5
1 parent ac8fe05
commit 7c193c5
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/...icalproperties/methods/commonphasephysicalproperties/viscosity/KTAViscosityMethodMod.java b/...icalproperties/methods/commonphasephysicalproperties/viscosity/KTAViscosityMethodMod.java
@@ -33,10 +33,12 @@ public double calcViscosity() {
     double P_crit = 0.22832;    // [MPa] (Source: NIST)
     double A = Math.pow((2 - T / 300), 5.05);
     double B = Math.pow((2 - 300 / T), 2) - 1;
+    double C = (1 - 0.3 / (1 + Math.exp(-0.5 * (T - 450)))) / (1 + Math.exp(-0.5 * (T - 377))) 
+                - 1.5 / (1 + Math.exp(-0.5 * (T - 572)));
     double viscosity = 1e-7 * (3.817 * Math.pow(T, 0.6938) 
                         + Math.pow(P, A) / (T * P_crit) 
                         + Math.exp(-Math.pow(T - 325, 2) / 1000) 
-                          * (Math.pow(P / 25, 2.7) - Math.pow(T, B)));
+                          * (Math.pow(P / 25, 2.7) - Math.pow(T, B)) - C);
     return viscosity;   // [Pa*s]
   }
 }