diff --git a/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/diffCoeffModel.C b/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/diffCoeffModel.C
index f216bc41..46ff5da2 100644
--- a/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/diffCoeffModel.C
+++ b/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/diffCoeffModel.C
@@ -73,7 +73,7 @@ diffCoeffModel::diffCoeffModel
     )
 {
     // build constant fields for single phase case
-    if (!particleCloud_.multiphase())
+    if (!particleCloud_.multiphase() && dict_.found("diffCoeffModel"))
     {
         D0Field_ = volScalarField
         (
diff --git a/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/newDiffCoeffModel.C b/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/newDiffCoeffModel.C
index cb27e7e7..0102c59a 100644
--- a/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/newDiffCoeffModel.C
+++ b/src/lagrangian/cfdemParticle/subModels/diffCoeffModel/diffCoeffModel/newDiffCoeffModel.C
@@ -37,7 +37,7 @@ autoPtr<diffCoeffModel> diffCoeffModel::New
 {
     word diffCoeffModelType
     (
-        dict.lookup("diffCoeffModel")
+        dict.lookupOrDefault<word>("diffCoeffModel","off")
     );
 
     Info<< "Selecting diffCoeffModel "