[staggeredGrid][nonisothermal] Fix diffusion_ni input file and Fourier's law

dumux/discretization/staggered/freeflow/fourierslaw.hh

@@ -97,7 +97,7 @@ public:
         const auto& insideScv = fvGeometry.scv(scvf.insideScvIdx());
         const auto& outsideScv = fvGeometry.scv(scvf.outsideScvIdx());
         const auto& insideVolVars = elemVolVars[insideScv];
-        const auto& outsideVolVars = scvf.boundary() ?  insideVolVars : elemVolVars[scvf.outsideScvIdx()];
+        const auto& outsideVolVars = elemVolVars[scvf.outsideScvIdx()];
 
         // effective conductivity tensors
         auto insideLambda = insideVolVars.thermalConductivity();

test/freeflow/staggeredni/test_diffusion_ni.input

 [TimeManager]
-DtInitial = 5e-3 # [s]
-TEnd = 1e-2 # [s]
+DtInitial = 1e-0 # [s]
+TEnd = 1.2e6 # [s]
 
 [Grid]
-UpperRight = 5 1
-Cells = 50 25
+UpperRight = 5 5
+Cells =  15 15
 
 [Problem]
 Name = test_diffusion_ni # name passed to the output routines
-InletVelocity = 5 #1000
 InletTemp = 293.15
 EnableGravity = false