diff --git a/src/lagrangian/molecularDynamics/molecule/moleculeCloud/moleculeCloud.C b/src/lagrangian/molecularDynamics/molecule/moleculeCloud/moleculeCloud.C
index b747373e3a..113fb82942 100644
--- a/src/lagrangian/molecularDynamics/molecule/moleculeCloud/moleculeCloud.C
+++ b/src/lagrangian/molecularDynamics/molecule/moleculeCloud/moleculeCloud.C
@@ -507,7 +507,7 @@ void Foam::moleculeCloud::initialiseMolecules
             else
             {
                 const dictionary& zoneDict =
-                mdInitialiseDict.subDict(zone.name());
+                    mdInitialiseDict.subDict(zone.name());
 
                 const scalar temperature
                 (
@@ -530,7 +530,7 @@ void Foam::moleculeCloud::initialiseMolecules
                 {
                     FatalErrorIn("Foam::moleculeCloud::initialiseMolecules")
                         << "latticeIds and latticePositions must be the same "
-                            << " size." << nl
+                        << " size." << nl
                         << abort(FatalError);
                 }
 
@@ -548,6 +548,15 @@ void Foam::moleculeCloud::initialiseMolecules
                         zoneDict.lookup("numberDensity")
                     );
 
+                    if (numberDensity < VSMALL)
+                    {
+                        WarningIn("moleculeCloud::initialiseMolecules")
+                            << "numberDensity too small, not filling zone "
+                            << zone.name() << endl;
+
+                        continue;
+                    }
+
                     latticeCellScale = pow
                     (
                         latticeIds.size()/(det(latticeCellShape)*numberDensity),
@@ -572,9 +581,19 @@ void Foam::moleculeCloud::initialiseMolecules
                         zoneDict.lookup("massDensity")
                     );
 
+                    if (massDensity < VSMALL)
+                    {
+                        WarningIn("moleculeCloud::initialiseMolecules")
+                            << "massDensity too small, not filling zone "
+                            << zone.name() << endl;
+
+                        continue;
+                    }
+
+
                     latticeCellScale = pow
                     (
-                        unitCellMass /(det(latticeCellShape)*massDensity),
+                        unitCellMass/(det(latticeCellShape)*massDensity),
                         (1.0/3.0)
                     );
                 }
@@ -906,7 +925,7 @@ void Foam::moleculeCloud::initialiseMolecules
                     )
                     {
                         WarningIn("Foam::moleculeCloud::initialiseMolecules()")
-                        << "A whole layer of unit cells was placed "
+                            << "A whole layer of unit cells was placed "
                             << "outside the bounds of the mesh, but no "
                             << "molecules have been placed in zone '"
                             << zone.name()
diff --git a/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/controlDict b/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/controlDict
index 8a3ba00616..51a42ecc0e 100644
--- a/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/controlDict
+++ b/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/controlDict
@@ -20,7 +20,7 @@ startTime       0;
 
 stopAt          endTime;
 
-endTime         1e-10;
+endTime         5e-12;
 
 deltaT          1e-15;
 
diff --git a/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/mdInitialiseDict b/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/mdInitialiseDict
index ac85160f5c..0d91d5a08b 100644
--- a/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/mdInitialiseDict
+++ b/tutorials/discreteMethods/molecularDynamics/mdFoam/nanoNozzle/system/mdInitialiseDict
@@ -27,7 +27,7 @@ FoamFile
 
 sectionA
 {
-    massDensity             980;
+    massDensity             1004;
     temperature             298;
     bulkVelocity            (0.0 0.0 0.0);
     latticeIds
@@ -46,7 +46,7 @@ sectionA
 
 sectionB
 {
-    massDensity             980;
+    massDensity             1004;
     temperature             298;
     bulkVelocity            (0.0 0.0 0.0);
     latticeIds
@@ -65,7 +65,7 @@ sectionB
 
 sectionC
 {
-    massDensity             980;
+    massDensity             1004;
     temperature             298;
     bulkVelocity            (0.0 0.0 0.0);
     latticeIds