diff --git a/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.C b/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.C
index 24bc155db0..f1cb956a57 100644
--- a/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.C
+++ b/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.C
@@ -336,6 +336,25 @@ Foam::tmp<Foam::vectorField> Foam::polyPatch::faceCellCentres() const
 }
 
 
+Foam::tmp<Foam::scalarField> Foam::polyPatch::areaFraction() const
+{
+    tmp<scalarField> tfraction(new scalarField(size()));
+    scalarField& fraction = tfraction.ref();
+
+    const vectorField::subField faceAreas = this->faceAreas();
+    const pointField& points = this->points();
+
+    forAll(*this, facei)
+    {
+        const face& curFace = this->operator[](facei);
+        fraction[facei] =
+            mag(faceAreas[facei])/(curFace.mag(points) + ROOTVSMALL);
+    }
+
+    return tfraction;
+}
+
+
 const Foam::labelUList& Foam::polyPatch::faceCells() const
 {
     if (!faceCellsPtr_)
diff --git a/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.H b/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.H
index 9de2d07b6a..d661304d52 100644
--- a/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.H
+++ b/src/OpenFOAM/meshes/polyMesh/polyPatches/polyPatch/polyPatch.H
@@ -373,6 +373,10 @@ public:
             //- Return face cell centres
             tmp<vectorField> faceCellCentres() const;
 
+            //- Return the area fraction as the ratio of the stored face area
+            //- and the area given by the face points
+            tmp<scalarField> areaFraction() const;
+
 
         // Addressing into mesh
 
diff --git a/src/lagrangian/basic/InteractionLists/InteractionLists.C b/src/lagrangian/basic/InteractionLists/InteractionLists.C
index 922ee09185..360f2a3cbc 100644
--- a/src/lagrangian/basic/InteractionLists/InteractionLists.C
+++ b/src/lagrangian/basic/InteractionLists/InteractionLists.C
@@ -324,10 +324,15 @@ void Foam::InteractionLists<ParticleType>::buildInteractionLists()
 
         if (isA<wallPolyPatch>(patch))
         {
-            localWallFaces.append
-            (
-                identity(patch.size(), patch.start())
-            );
+            const scalarField areaFraction(patch.areaFraction());
+
+            forAll(areaFraction, facei)
+            {
+                if (areaFraction[facei] > 0.5)
+                {
+                    localWallFaces.append(facei + patch.start());
+                }
+            }
         }
     }
 
@@ -335,10 +340,12 @@ void Foam::InteractionLists<ParticleType>::buildInteractionLists()
 
     forAll(wallFaceBbs, i)
     {
-        wallFaceBbs[i] = treeBoundBox
-        (
-            mesh_.faces()[localWallFaces[i]].points(mesh_.points())
-        );
+        wallFaceBbs[i] =
+            treeBoundBox
+            (
+                mesh_.points(),
+                mesh_.faces()[localWallFaces[i]]
+            );
     }
 
     // IAndT: index and transform
diff --git a/tutorials/incompressible/SRFPimpleFoam/rotor2D/0/epsilon b/tutorials/incompressible/SRFPimpleFoam/rotor2D/0/epsilon
index bc0943db35..e745051d37 100644
--- a/tutorials/incompressible/SRFPimpleFoam/rotor2D/0/epsilon
+++ b/tutorials/incompressible/SRFPimpleFoam/rotor2D/0/epsilon
@@ -24,7 +24,6 @@ boundaryField
     rotor
     {
         type            epsilonWallFunction;
-        U               Urel;
         value           uniform 3.75e-4;
     }
 
diff --git a/tutorials/incompressible/SRFSimpleFoam/mixer/0/epsilon b/tutorials/incompressible/SRFSimpleFoam/mixer/0/epsilon
index 63fc38dadb..5c7829c027 100644
--- a/tutorials/incompressible/SRFSimpleFoam/mixer/0/epsilon
+++ b/tutorials/incompressible/SRFSimpleFoam/mixer/0/epsilon
@@ -34,13 +34,11 @@ boundaryField
     innerWall
     {
         type            epsilonWallFunction;
-        U               Urel;
         value           uniform 14.855;
     }
     outerWall
     {
         type            epsilonWallFunction;
-        U               Urel;
         value           uniform 14.855;
     }
     cyclic_half0
diff --git a/tutorials/incompressible/SRFSimpleFoam/mixer/0/nut b/tutorials/incompressible/SRFSimpleFoam/mixer/0/nut
index 00a1844db8..2e05aa24b3 100644
--- a/tutorials/incompressible/SRFSimpleFoam/mixer/0/nut
+++ b/tutorials/incompressible/SRFSimpleFoam/mixer/0/nut
@@ -34,13 +34,11 @@ boundaryField
     innerWall
     {
         type            nutkWallFunction;
-        U               Urel;
         value           uniform 0;
     }
     outerWall
     {
         type            nutkWallFunction;
-        U               Urel;
         value           uniform 0;
     }
     cyclic_half0