diff --git a/doc/forceModel_ParmarBassetForce.txt b/doc/forceModel_ParmarBassetForce.txt
index bc022f53..a5e41730 100644
--- a/doc/forceModel_ParmarBassetForce.txt
+++ b/doc/forceModel_ParmarBassetForce.txt
@@ -30,12 +30,12 @@ ParmarBassetForceProps
 
 {U} = name of the finite volume fluid velocity field :ulb,l
 {Us} = name of the finite volume cell averaged particle velocity field :l
-{scalar1} = number of timesteps considered in the near history :l
-{scalar2} = (1 or 2) discretisation order of the far history differential equations :l
+{scalar1} = number of timesteps considered in the near history (integer > 1):l
+{scalar2} = (optional, default 1) discretisation order of the far history differential equations (1 or 2) :l
 {switch1} = (optional, default true) sub model switch, see "forceSubModel"_forceSubModel.html for details :l
 {switch2} = (optional, default false) sub model switch, see "forceSubModel"_forceSubModel.html for details :l
 {switch3} = (optional, default false) sub model switch, see "forceSubModel"_forceSubModel.html for details :l
-{smoothingModel} = name of smoothing model for the dU/dt field :l
+{smoothingModel} = name of smoothing model for the dUrel/dt field :l
 :ule
 
 [Examples:]
diff --git a/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.C b/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.C
index 2446796b..6ccc631b 100644
--- a/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.C
+++ b/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.C
@@ -70,8 +70,8 @@ ParmarBassetForce::ParmarBassetForce
     U_(sm.mesh().lookupObject<volVectorField> (velFieldName_)),
     UsFieldName_(propsDict_.lookup("granVelFieldName")),
     Us_(sm.mesh().lookupObject<volVectorField> (UsFieldName_)),
-    nInt_(readLabel(propsDict_.lookup("nIntegral"))),
-    discOrder_(readLabel(propsDict_.lookup("discretisationOrder"))),
+    nInt_(propsDict_.lookupOrDefault<int>("nIntegral", -1)),
+    discOrder_(propsDict_.lookupOrDefault<int>("discretisationOrder", 1)),
     ddtUrelHistSize_(nInt_+discOrder_),
     rHistSize_(nInt_),
     FHistSize_(2*discOrder_),
@@ -115,16 +115,6 @@ ParmarBassetForce::ParmarBassetForce
         )
     )
 {
-
-    // allocate particle properties
-    particleCloud_.registerParticleProperty<double**>(ddtUrelHistRegName_,3*ddtUrelHistSize_,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(      rHistRegName_,        rHistSize_,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(      FHistRegName_,      6*FHistSize_,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(        gH0RegName_,                1 ,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(       tRefRegName_,                1 ,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(       mRefRegName_,                1 ,NOTONCPU,false);
-    particleCloud_.registerParticleProperty<double**>(       lRefRegName_,                1 ,NOTONCPU,false);
-
     // init force sub model
     setForceSubModels(propsDict_);
     // define switches which can be read from dict
@@ -139,6 +129,18 @@ ParmarBassetForce::ParmarBassetForce
     if (discOrder_ < 1 || discOrder_ > 2)
         FatalError << "Parmar Basset Force: Discretisation order > 2 not implemented!" << abort(FatalError);
 
+    if (nInt_ < 1)
+        FatalError << "Parmar Basset Force: nIntegral missing or invalid, must be > 1" << abort(FatalError);
+
+    // allocate particle properties
+    particleCloud_.registerParticleProperty<double**>(ddtUrelHistRegName_,3*ddtUrelHistSize_,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(      rHistRegName_,        rHistSize_,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(      FHistRegName_,      6*FHistSize_,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(        gH0RegName_,                1 ,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(       tRefRegName_,                1 ,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(       mRefRegName_,                1 ,NOTONCPU,false);
+    particleCloud_.registerParticleProperty<double**>(       lRefRegName_,                1 ,NOTONCPU,false);
+
     //Append the field names to be probed
     particleCloud_.probeM().initialize(typeName, typeName+".logDat");
     particleCloud_.probeM().vectorFields_.append("ParmarBassetForce"); //first entry must the be the force
diff --git a/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.H b/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.H
index 1d89695d..122e9172 100644
--- a/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.H
+++ b/src/lagrangian/cfdemParticle/subModels/forceModel/ParmarBassetForce/ParmarBassetForce.H
@@ -59,23 +59,23 @@ class ParmarBassetForce
 private:
     dictionary propsDict_;
 
-    word velFieldName_;
+    const word velFieldName_;
 
     const volVectorField& U_;
 
-    word UsFieldName_;
+    const word UsFieldName_;
 
     const volVectorField& Us_;
 
-    label nInt_;                            //no of timesteps to solve full integral
+    const int nInt_;                            //no of timesteps to solve full integral
 
-    label discOrder_;                       //ODE discretisation order
+    const int discOrder_;                       //ODE discretisation order
 
-    label ddtUrelHistSize_;                 //no of timesteps to save ddtUrel history for
+    const int ddtUrelHistSize_;                 //no of timesteps to save ddtUrel history for
 
-    label rHistSize_;                       //no of timesteps to save r history for
+    const int rHistSize_;                       //no of timesteps to save r history for
 
-    label FHistSize_;                       //no of timesteps to save Flong history for
+    const int FHistSize_;                       //no of timesteps to save Flong history for
 
     const word ddtUrelHistRegName_;