ENH: windTurbineFoam : roughtNutWallFunction needs scalarField for roughness

tutorials/incompressible/simpleFoam/windTurbineTerrain/0/nut

@@ -37,8 +37,8 @@ boundaryField
     "terrain_.*"
     {
         type            nutkRoughWallFunction;
-        Ks              0.2; //Ks = 20 Z0
-        Cs              0.5;
+        Ks              uniform 0.2; //Ks = 20 Z0
+        Cs              uniform 0.5;
         value           uniform 0.0;
     }