couplinglocalresiduals. this is done in consistency with the freeflow
stokes models. the eddy coefficient are zero for the stokes case.

approved by gruenich


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@12738 2fb0f335-1f38-0410-981e-8018bf24f1b0