Check patch type to be wall before moving face reference point.

src/lagrangian/basic/Particle/ParticleI.H

@@ -193,18 +193,24 @@ inline Foam::scalar Foam::Particle<ParticleType>::lambda
     // move reference point for wall
     if (!cloud_.internalFace(facei))
     {
-        const vector& C = mesh.cellCentres()[celli_];
-        scalar CCf = mag((C - Cf) & Sf);
-        // check if distance between cell centre and face centre
-        // is larger than wallImpactDistance
-        if
-        (
-            CCf
-          > static_cast<const ParticleType&>(*this).wallImpactDistance(Sf)
-        )
+        label patchi = mesh.boundaryMesh().whichPatch(facei);
+        const polyPatch& patch = mesh.boundaryMesh()[patchi];
+
+        if (isA<wallPolyPatch>(patch))
         {
-            Cf -= static_cast<const ParticleType&>(*this)
-                .wallImpactDistance(Sf)*Sf;
+            const vector& C = mesh.cellCentres()[celli_];
+            scalar CCf = mag((C - Cf) & Sf);
+            // check if distance between cell centre and face centre
+            // is larger than wallImpactDistance
+            if
+            (
+                CCf
+              > static_cast<const ParticleType&>(*this).wallImpactDistance(Sf)
+            )
+            {
+                Cf -= static_cast<const ParticleType&>(*this)
+                    .wallImpactDistance(Sf)*Sf;
+            }
         }
     }