particle: Removed the oldNormal function which is no longer needed

src/lagrangian/basic/particle/particle.H

@@ -471,11 +471,6 @@ public:
             //  current tet.
             inline vector normal() const;
 
-            //- Return the normal of the tri on tetFacei_ for the
-            //  current tet at the start of the timestep, i.e. based
-            //  on oldPoints
-            inline vector oldNormal() const;
-
             //- Is the particle on a face?
             inline bool onFace() const;
 

src/lagrangian/basic/particle/particleI.H

@@ -256,12 +256,6 @@ inline Foam::vector Foam::particle::normal() const
 }
 
 
-inline Foam::vector Foam::particle::oldNormal() const
-{
-    return currentTetIndices().oldFaceTri(mesh_).normal();
-}
-
-
 inline bool Foam::particle::onFace() const
 {
     return facei_ >= 0;