Regularize the reduced temperature beyond the critical point of water. This...

Regularize the reduced temperature beyond the critical point of water. This will *not* lead to physically meaningful results, but increases stability if there are intermediate hot states in a simulation. 

reviewed by Benjamin

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@12425 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/material/binarycoefficients/henryiapws.hh

@@ -39,6 +39,10 @@ namespace Dumux
  * Distribution Constant for Gases in H2O and D2O at High
  * Temperatures"
  * http://www.iapws.org/relguide/HenGuide.pdf
+ *
+ * Range of validity: T = {278.12 ; 636.46}
+ * approximations beyond this range are increasingly incorrect.
+ * However, close to the critical the values are more, again.
  */
 template <class Scalar>
 inline Scalar henryIAPWS(Scalar E,
@@ -49,6 +53,11 @@ inline Scalar henryIAPWS(Scalar E,
 {
     typedef Dumux::H2O<Scalar> H2O;
 
+    // regularizing temperature helps for stability.
+    // Results are unphysical!
+    if (temperature > H2O::criticalTemperature()  )
+    	temperature = H2O::criticalTemperature()  ;
+
     Scalar Tr = temperature/H2O::criticalTemperature();
     Scalar tau = 1 - Tr;