BUG: motionSmoother: knock out displacement on points coupled to patch points

Before was zeroing displacement on all coupled points before
applying the displacement. This meant that we could not modify the
internal displacement on coupled points before setting the patch displacement.
Fixes #10.

src/dynamicMesh/motionSmoother/motionSmootherAlgo.C

@@ -514,12 +514,31 @@ void Foam::motionSmootherAlgo::setDisplacement
     const labelList& cppMeshPoints =
         mesh.globalData().coupledPatch().meshPoints();
 
+    const labelList& ppMeshPoints = pp.meshPoints();
+
+    // Knock out displacement on points which are not on pp but are coupled
+    // to them since we want 'proper' values from displacement to take
+    // precedence.
+    {
+        PackedBoolList isPatchPoint(mesh.nPoints());
+        isPatchPoint.set(ppMeshPoints);
+        syncTools::syncPointList
+        (
+            mesh,
+            isPatchPoint,
+            maxEqOp<unsigned int>(),
+            0
+        );
         forAll(cppMeshPoints, i)
         {
-        displacement[cppMeshPoints[i]] = vector::zero;
+            label pointI = cppMeshPoints[i];
+            if (isPatchPoint[pointI])
+            {
+                displacement[pointI] = vector::zero;
+            }
+        }
     }
 
-    const labelList& ppMeshPoints = pp.meshPoints();
 
     // Set internal point data from displacement on combined patch points.
     forAll(ppMeshPoints, patchPointI)

src/dynamicMesh/motionSmoother/motionSmootherAlgo.H

@@ -56,7 +56,8 @@ Note
     and/or edges but no faces of pp). Hence we have to be careful when e.g.
     synchronising displacements that the value from the processor which has
     faces of pp get priority. This is currently handled in setDisplacement
-    by resetting the internal displacement to zero before doing anything
+    by resetting the internal displacement to zero on coupled points
+    that are coupled to patch points before doing anything
     else. The combine operator used will give preference to non-zero
     values.