ENH: Changing BC for U to slip

tutorials/compressible/overRhoSimpleFoam/hotCylinder/cylinderAndBackground/0.orig/U

@@ -45,9 +45,7 @@ boundaryField
 
     topAndBottom
     {
-        type            inletOutlet;
-        inletValue      uniform (0 0 0);
-        value           $internalField;
+        type            slip;
     }
 }