MULES: Adjust limiter only at boundaries for which the field value is fixed

Resolves bug-report https://bugs.openfoam.org/view.php?id=2470

src/finiteVolume/fvMatrices/solvers/MULES/CMULESTemplates.C

@@ -259,6 +259,16 @@ void Foam::MULES::limiterCorr
                 psiMinn[pfCelli] = min(psiMinn[pfCelli], psiPf[pFacei]);
             }
         }
+        else
+        {
+            forAll(phiCorrPf, pFacei)
+            {
+                const label pfCelli = pFaceCells[pFacei];
+
+                psiMaxn[pfCelli] = max(psiMaxn[pfCelli], psiMax);
+                psiMinn[pfCelli] = min(psiMinn[pfCelli], psiMin);
+            }
+        }
 
         forAll(phiCorrPf, pFacei)
         {

src/finiteVolume/fvMatrices/solvers/MULES/MULESTemplates.C

@@ -301,6 +301,16 @@ void Foam::MULES::limiter
                 psiMinn[pfCelli] = min(psiMinn[pfCelli], psiPf[pFacei]);
             }
         }
+        else
+        {
+            forAll(phiCorrPf, pFacei)
+            {
+                const label pfCelli = pFaceCells[pFacei];
+
+                psiMaxn[pfCelli] = max(psiMaxn[pfCelli], psiMax);
+                psiMinn[pfCelli] = min(psiMinn[pfCelli], psiMin);
+            }
+        }
 
         forAll(phiCorrPf, pFacei)
         {