The averaged viscosity is used for the computation of mu grad v (part of the...

The averaged viscosity is used for the computation of mu grad v (part of the momentum flux) instead of upwinding

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@7948 2fb0f335-1f38-0410-981e-8018bf24f1b0