Bugfix: Computation of thermal conductivity according to Somerton was wrong

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@10327 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/material/fluidmatrixinteractions/2p/thermalconductivitysomerton.hh

@@ -48,7 +48,7 @@ public:
      *
      * The material law is:
      * \f[
-     l_eff = l_solid + (l_wet - l_solid)
+     l_eff = l_solid + \sqrt(S_w)(l_wet - l_solid)
      \f]
      *
      * \param Sw The saturation of the wetting phase
@@ -69,9 +69,8 @@ public:
         const Scalar lSat = std::pow(lambdaSolid, (1.0 - porosity)) * std::pow(lambdaW, porosity);
         const Scalar lDry = std::pow(lambdaSolid, (1.0 - porosity));
 
-        return lDry + std::sqrt(satW) * (lDry - lSat);
+        return lDry + std::sqrt(satW) * (lSat - lDry);
     }
-
 };
 }
 #endif