diff --git a/src/lagrangian/basic/InteractionLists/DirectInteractionList/DirectInteractionList.C b/src/lagrangian/basic/InteractionLists/DirectInteractionList/DirectInteractionList.C
index d7a5cb28bd..4f53af759f 100644
--- a/src/lagrangian/basic/InteractionLists/DirectInteractionList/DirectInteractionList.C
+++ b/src/lagrangian/basic/InteractionLists/DirectInteractionList/DirectInteractionList.C
@@ -35,7 +35,7 @@ void Foam::DirectInteractionList<ParticleType>::buildDirectInteractionList
     bool pointPointListBuild
 )
 {
-    Info<< nl << "Building list of direct interaction neighbours" << endl;
+    Info<< "    Building list of direct interaction neighbours" << endl;
 
     const polyMesh& mesh(il_.mesh());
 
@@ -43,7 +43,7 @@ void Foam::DirectInteractionList<ParticleType>::buildDirectInteractionList
 
     if (pointPointListBuild)
     {
-        Info<< tab << "Point-Point direct interaction list build." << endl;
+        Info<< "        Point-Point direct interaction list build." << endl;
 
         label pointJIndex;
 
@@ -116,7 +116,7 @@ void Foam::DirectInteractionList<ParticleType>::buildDirectInteractionList
     }
     else
     {
-        Info<< tab << "Point-Face, Edge-Edge direct interaction list build."
+        Info<< "        Point-Face, Edge-Edge direct interaction list build."
             << endl;
 
         forAll(mesh.points(), p)
@@ -319,8 +319,7 @@ Foam::DirectInteractionList<ParticleType>::DirectInteractionList
     }
     else if ((*this).size() == 1)
     {
-        Info<< nl
-            << "Single cell mesh, no direct interaction lists required."
+        Info<< "    Single cell mesh, no direct interaction lists required."
             << endl;
 
         (*this)[0].setSize(0);
@@ -337,7 +336,7 @@ Foam::DirectInteractionList<ParticleType>::DirectInteractionList
     labelListList(il.mesh().nCells()),
     il_(il)
 {
-    Info<< "Read DirectInteractionList from disk not implemented" << endl;
+    Info<< "    Read DirectInteractionList from disk not implemented" << endl;
 }
 
 
diff --git a/src/lagrangian/basic/InteractionLists/InteractionLists.C b/src/lagrangian/basic/InteractionLists/InteractionLists.C
index d63392033e..60720e325c 100644
--- a/src/lagrangian/basic/InteractionLists/InteractionLists.C
+++ b/src/lagrangian/basic/InteractionLists/InteractionLists.C
@@ -37,7 +37,7 @@ Foam::scalar Foam::InteractionLists<ParticleType>::transTol = 1e-12;
 template<class ParticleType>
 void Foam::InteractionLists<ParticleType>::buildCellReferralLists()
 {
-    Info<< nl << "Determining particle referring schedule" << endl;
+    Info<< "    Determining particle referring schedule" << endl;
 
     const ReferredCellList<ParticleType>& refIntL(ril());
 
diff --git a/src/lagrangian/basic/InteractionLists/ReferredCellList/ReferredCellList.C b/src/lagrangian/basic/InteractionLists/ReferredCellList/ReferredCellList.C
index 329af4f197..58bfdf3a9a 100644
--- a/src/lagrangian/basic/InteractionLists/ReferredCellList/ReferredCellList.C
+++ b/src/lagrangian/basic/InteractionLists/ReferredCellList/ReferredCellList.C
@@ -41,7 +41,7 @@ void Foam::ReferredCellList<ParticleType>::buildReferredCellList
     bool pointPointListBuild
 )
 {
-    Info << nl << "Building list of referred interaction neighbours" << endl;
+    Info<< "    Building list of referred interaction neighbours" << endl;
 
     const polyMesh& mesh(il_.mesh());
 
@@ -1272,7 +1272,7 @@ void Foam::ReferredCellList<ParticleType>::buildReferredCellList
 
         reduce(cellsReferredThisIteration, sumOp<label>());
 
-        Info<< tab << "Cells added this iteration: "
+        Info<< "        Cells added this iteration: "
             << cellsReferredThisIteration << endl;
     }
 
@@ -1288,7 +1288,7 @@ void Foam::ReferredCellList<ParticleType>::buildReferredCellList
         (*this)[rIL] = referredInteractionList[rIL];
     }
 
-    Info<< nl << "Finding real cells in range of referred cells" << endl;
+    Info<< "    Finding real cells in range of referred cells" << endl;
 
     forAll(*this, rC)
     {
@@ -1487,7 +1487,7 @@ Foam::ReferredCellList<ParticleType>::ReferredCellList
     il_(il),
     cloud_(il_.mesh(), IDLList<ParticleType>())
 {
-    Info<< "Read ReferredCellList from disk not implemented" << endl;
+    Info<< "    Read ReferredCellList from disk not implemented" << endl;
 }
 
 
diff --git a/src/lagrangian/intermediate/parcels/include/makeParcelCollisionModels.H b/src/lagrangian/intermediate/parcels/include/makeParcelCollisionModels.H
index 1729e54c62..526bc2c52e 100644
--- a/src/lagrangian/intermediate/parcels/include/makeParcelCollisionModels.H
+++ b/src/lagrangian/intermediate/parcels/include/makeParcelCollisionModels.H
@@ -32,7 +32,9 @@ License
 #include "InteractingKinematicCloud.H"
 
 #include "NoCollision.H"
-#include "DeterministicPairForce.H"
+#include "PairCollision.H"
+
+#include "SpringSliderDashpot.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -49,10 +51,20 @@ License
                                                                               \
     makeCollisionModelType                                                    \
     (                                                                         \
-        DeterministicPairForce,                                               \
+        PairCollision,                                                        \
         InteractingKinematicCloud,                                            \
         ParcelType                                                            \
     );                                                                        \
+                                                                              \
+    makePairFunction(InteractingKinematicCloud<ParcelType>);                  \
+                                                                              \
+    makePairFunctionType                                                      \
+    (                                                                         \
+        SpringSliderDashpot,                                                  \
+        InteractingKinematicCloud,                                            \
+        ParcelType                                                            \
+    );
+
 
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/lagrangian/intermediate/parcels/include/makeReactingParcelCollisionModels.H b/src/lagrangian/intermediate/parcels/include/makeReactingParcelCollisionModels.H
index eabb5cb4de..92541862b1 100644
--- a/src/lagrangian/intermediate/parcels/include/makeReactingParcelCollisionModels.H
+++ b/src/lagrangian/intermediate/parcels/include/makeReactingParcelCollisionModels.H
@@ -33,7 +33,9 @@ License
 #include "InteractingKinematicCloud.H"
 
 #include "NoCollision.H"
-#include "DeterministicPairForce.H"
+#include "PairCollision.H"
+
+#include "SpringSliderDashpot.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -72,9 +74,19 @@ License
                                                                               \
     makeCollisionModelThermoType                                              \
     (                                                                         \
-        DeterministicPairForce,                                               \
+        PairCollision,                                                        \
         InteractingKinematicCloud,                                            \
-        ParcelType,                                                            \
+        ParcelType,                                                           \
+        ThermoType                                                            \
+    );                                                                        \
+                                                                              \
+    makePairFunction(InteractingKinematicCloud<ParcelType<ThermoType> >);     \
+                                                                              \
+    makePairFunctionThermoType                                                \
+    (                                                                         \
+        SpringSliderDashpot,                                                  \
+        InteractingKinematicCloud,                                            \
+        ParcelType,                                                           \
         ThermoType                                                            \
     );
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/CollisionModel/CollisionModel.H b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/CollisionModel/CollisionModel.H
index 84e7a3a771..eef25ff7dd 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/CollisionModel/CollisionModel.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/CollisionModel/CollisionModel.H
@@ -73,16 +73,6 @@ protected:
         typedef typename CloudType::parcelType parcelType;
 
 
-    // Protected member functions
-
-        //- Calculate the pair force between parcels
-        virtual void evaluatePair
-        (
-            typename CloudType::parcelType& pA,
-            typename CloudType::parcelType& pB
-        ) const = 0;
-
-
 public:
 
     //- Runtime type information
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.C b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.C
index fbd3c231ad..e80335be87 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.C
@@ -26,18 +26,6 @@ License
 
 #include "NoCollision.H"
 
-// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
-
-template<class CloudType>
-void Foam::NoCollision<CloudType>::evaluatePair
-(
-    typename CloudType::parcelType& pA,
-    typename CloudType::parcelType& pB
-) const
-{
-
-}
-
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template<class CloudType>
@@ -69,9 +57,7 @@ bool Foam::NoCollision<CloudType>::active() const
 
 template<class CloudType>
 void Foam::NoCollision<CloudType>::collide()
-{
-
-}
+{}
 
 
 // ************************************************************************* //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.H b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.H
index 3f19e2b31d..9316043259 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/NoCollision/NoCollision.H
@@ -43,7 +43,7 @@ namespace Foam
 {
 
 /*---------------------------------------------------------------------------*\
-                     Class NoCollision Declaration
+                        Class NoCollision Declaration
 \*---------------------------------------------------------------------------*/
 
 template<class CloudType>
@@ -52,18 +52,6 @@ class NoCollision
     public CollisionModel<CloudType>
 {
 
-protected:
-
-    // Protected member functions
-
-        //- Calculate the pair force between parcels
-        virtual void evaluatePair
-        (
-            typename CloudType::parcelType& pA,
-            typename CloudType::parcelType& pB
-        ) const;
-
-
 public:
 
     //- Runtime type information
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.C b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.C
similarity index 79%
rename from src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.C
rename to src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.C
index e96532c188..54795112bb 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.C
@@ -24,12 +24,13 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "DeterministicPairForce.H"
+#include "PairCollision.H"
+#include "PairFunction.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
 template<class CloudType>
-void Foam::DeterministicPairForce<CloudType>::buildCellOccupancy()
+void Foam::PairCollision<CloudType>::buildCellOccupancy()
 {
     Info<< "Build cell occupancy" << endl;
 
@@ -46,53 +47,21 @@ void Foam::DeterministicPairForce<CloudType>::buildCellOccupancy()
     il_.ril().referParticles(cellOccupancy_);
 }
 
-// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
 
 template<class CloudType>
-void Foam::DeterministicPairForce<CloudType>::evaluatePair
+void Foam::PairCollision<CloudType>::evaluatePair
 (
     typename CloudType::parcelType& pA,
     typename CloudType::parcelType& pB
 ) const
 {
-    vector deltaP = (pB.position() - pA.position());
-
-    scalar deltaN = 0.5*(pA.d() + pB.d()) - mag(deltaP);
-
-    if (deltaN > 0)
-    {
-        //Particles in collision
-
-        vector n = deltaP/(mag(deltaP) + VSMALL);
-
-        vector Urel = pA.U() - pB.U();
-
-        // Effective radius
-        scalar R = 0.5*pA.d()*pB.d()/(pA.d() + pB.d());
-
-        // Effective mass
-        scalar M = pA.mass()*pB.mass()/(pA.mass() + pB.mass());
-
-        scalar E = 2e3;
-        scalar sigma = 0.25;
-        scalar alpha = 0.2;
-        scalar b = 1.0;
-
-        scalar Estar = E/(2.0*(1-sqr(sigma)));
-        scalar kN = (4.0/3.0)*sqrt(R)*Estar;
-        scalar etaN = alpha*sqrt(M*kN)*pow(deltaN, 0.25);
-
-        vector normalForce = -(kN*pow(deltaN, b) + etaN*(Urel & n))*n;
-
-        pA.f() += normalForce;
-        pB.f() -= normalForce;
-    }
+    pairFunction_->evaluatePair(pA, pB);
 }
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 template<class CloudType>
-Foam::DeterministicPairForce<CloudType>::DeterministicPairForce
+Foam::PairCollision<CloudType>::PairCollision
 (
     const dictionary& dict,
     CloudType& owner
@@ -100,6 +69,14 @@ Foam::DeterministicPairForce<CloudType>::DeterministicPairForce
 :
     CollisionModel<CloudType>(dict, owner, typeName),
     cellOccupancy_(owner.mesh().nCells()),
+    pairFunction_
+    (
+        PairFunction<CloudType>::New
+        (
+            this->coeffDict(),
+            this->owner()
+        )
+    ),
     il_(owner.mesh(), 2.6e-5, true)
 {
     Info<< "SEARCH DISTANCE SQR HARD CODED" << endl;
@@ -109,21 +86,21 @@ Foam::DeterministicPairForce<CloudType>::DeterministicPairForce
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
 template<class CloudType>
-Foam::DeterministicPairForce<CloudType>::~DeterministicPairForce()
+Foam::PairCollision<CloudType>::~PairCollision()
 {}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class CloudType>
-bool Foam::DeterministicPairForce<CloudType>::active() const
+bool Foam::PairCollision<CloudType>::active() const
 {
     return true;
 }
 
 
 template<class CloudType>
-void Foam::DeterministicPairForce<CloudType>::collide()
+void Foam::PairCollision<CloudType>::collide()
 {
     Info<< "Calculating collisions" << endl;
 
@@ -219,7 +196,6 @@ void Foam::DeterministicPairForce<CloudType>::collide()
         }
     }
 
-
     Info<< "ADD COLLISIONS WITH WALLS HERE, DOES NOT NEED TO BE A TRACKING "
         << "OPERATION.  CALCULATE DISTANCE TO SURFACES OF WALL TYPE AND APPLY "
         << "WALL FORCE MODEL" << endl;
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.H b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.H
similarity index 85%
rename from src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.H
rename to src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.H
index 728bdece45..79228f239b 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/DeterministicPairForce/DeterministicPairForce.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairCollision.H
@@ -23,17 +23,17 @@ License
     Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 
 Class
-    Foam::DeterministicPairForce
+    Foam::PairCollision
 
 Description
 
 SourceFiles
-    DeterministicPairForce.C
+    PairCollision.C
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef DeterministicPairForce_H
-#define DeterministicPairForce_H
+#ifndef PairCollision_H
+#define PairCollision_H
 
 #include "CollisionModel.H"
 #include "InteractionLists.H"
@@ -43,12 +43,18 @@ SourceFiles
 namespace Foam
 {
 
+// Forward declaration of classes
+
+template<class CloudType>
+class PairFunction;
+
+
 /*---------------------------------------------------------------------------*\
-                     Class DeterministicPairForce Declaration
+                     Class PairCollision Declaration
 \*---------------------------------------------------------------------------*/
 
 template<class CloudType>
-class DeterministicPairForce
+class PairCollision
 :
     public CollisionModel<CloudType>
 {
@@ -57,6 +63,9 @@ class DeterministicPairForce
         //- Cell occupancy information for each parcel
         List<DynamicList<typename CloudType::parcelType*> > cellOccupancy_;
 
+        // //- PairFunction to calculate the interaction between two parcels
+        autoPtr<PairFunction<CloudType> > pairFunction_;
+
         //- Interactions lists determining which cells are in
         //  interaction range of each other
         InteractionLists<typename CloudType::parcelType> il_;
@@ -67,13 +76,8 @@ class DeterministicPairForce
         //- Build the cell occupancy information for each parcel
         void buildCellOccupancy();
 
-
-protected:
-
-    // Protected member functions
-
         //- Calculate the pair force between parcels
-        virtual void evaluatePair
+        void evaluatePair
         (
             typename CloudType::parcelType& pA,
             typename CloudType::parcelType& pB
@@ -83,13 +87,13 @@ protected:
 public:
 
     //- Runtime type information
-    TypeName("DeterministicPairForce");
+    TypeName("PairCollision");
 
 
     // Constructors
 
         //- Construct from dictionary
-        DeterministicPairForce
+        PairCollision
         (
             const dictionary& dict,
             CloudType& owner
@@ -97,7 +101,7 @@ public:
 
 
     //- Destructor
-    virtual ~DeterministicPairForce();
+    virtual ~PairCollision();
 
 
     // Member Functions
@@ -117,7 +121,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-#   include "DeterministicPairForce.C"
+#   include "PairCollision.C"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/NewPairFunction.C b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/NewPairFunction.C
new file mode 100644
index 0000000000..693198b2d4
--- /dev/null
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/NewPairFunction.C
@@ -0,0 +1,67 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software; you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation; either version 2 of the License, or (at your
+    option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+\*---------------------------------------------------------------------------*/
+
+#include "PairFunction.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<class CloudType>
+Foam::autoPtr<Foam::PairFunction<CloudType> >
+Foam::PairFunction<CloudType>::New
+(
+    const dictionary& dict,
+    CloudType& owner
+)
+{
+    word PairFunctionType(dict.lookup("PairFunction"));
+
+    Info<< "Selecting PairFunction " << PairFunctionType
+        << endl;
+
+    typename dictionaryConstructorTable::iterator cstrIter =
+        dictionaryConstructorTablePtr_->find(PairFunctionType);
+
+    if (cstrIter == dictionaryConstructorTablePtr_->end())
+    {
+        FatalErrorIn
+        (
+            "PairFunction<CloudType>::New"
+            "("
+                "const dictionary&, "
+                "CloudType&"
+            ")"
+        )   << "Unknown PairFunctionType type "
+            << PairFunctionType
+            << ", constructor not in hash table" << nl << nl
+            << "    Valid PairFunction types are:" << nl
+            << dictionaryConstructorTablePtr_->sortedToc() << exit(FatalError);
+    }
+
+    return autoPtr<PairFunction<CloudType> >(cstrIter()(dict, owner));
+}
+
+
+// ************************************************************************* //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.C b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.C
new file mode 100644
index 0000000000..6f78362035
--- /dev/null
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.C
@@ -0,0 +1,81 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software; you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation; either version 2 of the License, or (at your
+    option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+\*---------------------------------------------------------------------------*/
+
+#include "PairFunction.H"
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template<class CloudType>
+Foam::PairFunction<CloudType>::PairFunction
+(
+    const dictionary& dict,
+    CloudType& owner,
+    const word& type
+)
+:
+    dict_(dict),
+    owner_(owner),
+    coeffDict_(dict.subDict(type + "Coeffs"))
+{}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+template<class CloudType>
+Foam::PairFunction<CloudType>::~PairFunction()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class CloudType>
+const CloudType&
+Foam::PairFunction<CloudType>::owner() const
+{
+    return owner_;
+}
+
+
+template<class CloudType>
+const Foam::dictionary& Foam::PairFunction<CloudType>::dict() const
+{
+    return dict_;
+}
+
+
+template<class CloudType>
+const Foam::dictionary&
+Foam::PairFunction<CloudType>::coeffDict() const
+{
+    return coeffDict_;
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "NewPairFunction.C"
+
+// ************************************************************************* //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.H b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.H
new file mode 100644
index 0000000000..2248f7feb7
--- /dev/null
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/PairFunction/PairFunction.H
@@ -0,0 +1,183 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software; you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation; either version 2 of the License, or (at your
+    option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+Class
+    Foam::PairFunction
+
+Description
+    Templated pair interaction class
+
+SourceFiles
+    PairFunction.C
+    NewPairFunction.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef PairFunction_H
+#define PairFunction_H
+
+#include "IOdictionary.H"
+#include "autoPtr.H"
+#include "runTimeSelectionTables.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                   Class PairFunction Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class CloudType>
+class PairFunction
+{
+    // Private data
+
+        //- The cloud dictionary
+        const dictionary& dict_;
+
+        //- Reference to the owner cloud class
+        CloudType& owner_;
+
+        //- The coefficients dictionary
+        const dictionary coeffDict_;
+
+
+public:
+
+    //- Runtime type information
+    TypeName("PairFunction");
+
+    //- Declare runtime constructor selection table
+    declareRunTimeSelectionTable
+    (
+        autoPtr,
+        PairFunction,
+        dictionary,
+        (
+            const dictionary& dict,
+            CloudType& owner
+        ),
+        (dict, owner)
+    );
+
+
+    // Constructors
+
+        //- Construct from components
+        PairFunction
+        (
+            const dictionary& dict,
+            CloudType& owner,
+            const word& type
+        );
+
+
+    //- Destructor
+    virtual ~PairFunction();
+
+
+    //- Selector
+    static autoPtr<PairFunction<CloudType> > New
+    (
+        const dictionary& dict,
+        CloudType& owner
+    );
+
+
+    // Access
+
+        //- Return the owner cloud object
+        const CloudType& owner() const;
+
+        //- Return the dictionary
+        const dictionary& dict() const;
+
+        //- Return the coefficients dictionary
+        const dictionary& coeffDict() const;
+
+
+    // Member Functions
+
+        //- Calculate the pair interaction between parcels
+        virtual void evaluatePair
+        (
+            typename CloudType::parcelType& pA,
+            typename CloudType::parcelType& pB
+        ) const = 0;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#define makePairFunction(CloudType)                                           \
+                                                                              \
+    defineNamedTemplateTypeNameAndDebug(PairFunction<CloudType>, 0);          \
+                                                                              \
+    defineTemplateRunTimeSelectionTable                                       \
+    (                                                                         \
+        PairFunction<CloudType>,                                              \
+        dictionary                                                            \
+    );
+
+
+#define makePairFunctionType(SS, CloudType, ParcelType)                       \
+                                                                              \
+    defineNamedTemplateTypeNameAndDebug(SS<CloudType<ParcelType> >, 0);       \
+                                                                              \
+    PairFunction<CloudType<ParcelType> >::                                    \
+        adddictionaryConstructorToTable<SS<CloudType<ParcelType> > >          \
+            add##SS##CloudType##ParcelType##ConstructorToTable_;
+
+
+#define makePairFunctionThermoType(SS, CloudType, ParcelType, ThermoType)     \
+                                                                              \
+    defineNamedTemplateTypeNameAndDebug                                       \
+    (                                                                         \
+        SS<CloudType<ParcelType<ThermoType> > >,                              \
+        0                                                                     \
+    );                                                                        \
+                                                                              \
+    PairFunction<CloudType<ParcelType<ThermoType> > >::                       \
+        adddictionaryConstructorToTable                                       \
+            <SS<CloudType<ParcelType<ThermoType> > > >                        \
+            add##SS##CloudType##ParcelType##ThermoType##ConstructorToTable_;
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+#   include "PairFunction.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.C b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.C
new file mode 100644
index 0000000000..c8d3e0cd37
--- /dev/null
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.C
@@ -0,0 +1,101 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software; you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation; either version 2 of the License, or (at your
+    option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+\*---------------------------------------------------------------------------*/
+
+#include "SpringSliderDashpot.H"
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template <class CloudType>
+Foam::SpringSliderDashpot<CloudType>::SpringSliderDashpot
+(
+    const dictionary& dict,
+    CloudType& cloud
+)
+:
+    PairFunction<CloudType>(dict, cloud, typeName),
+    Estar_(),
+    Gstar_(),
+    sigma_(dimensionedScalar(this->coeffDict().lookup("sigma")).value()),
+    alpha_(dimensionedScalar(this->coeffDict().lookup("alpha")).value()),
+    b_(dimensionedScalar(this->coeffDict().lookup("b")).value())
+{
+    scalar E = dimensionedScalar(this->coeffDict().lookup("E")).value();
+
+    Estar_ = E/(2.0*(1.0 - sqr(sigma_)));
+
+    scalar G = E/(2.0*(1.0 + sigma_));
+
+    Gstar_ = G/(2.0*(2.0 - sigma_));
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+template <class CloudType>
+Foam::SpringSliderDashpot<CloudType>::~SpringSliderDashpot()
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class CloudType>
+void Foam::SpringSliderDashpot<CloudType>::evaluatePair
+(
+    typename CloudType::parcelType& pA,
+    typename CloudType::parcelType& pB
+) const
+{
+    vector deltaP = (pB.position() - pA.position());
+
+    scalar deltaN = 0.5*(pA.d() + pB.d()) - mag(deltaP);
+
+    if (deltaN > 0)
+    {
+        //Particles in collision
+
+        vector n = deltaP/(mag(deltaP) + VSMALL);
+
+        vector Urel = pA.U() - pB.U();
+
+        // Effective radius
+        scalar R = 0.5*pA.d()*pB.d()/(pA.d() + pB.d());
+
+        // Effective mass
+        scalar M = pA.mass()*pB.mass()/(pA.mass() + pB.mass());
+
+        scalar kN = (4.0/3.0)*sqrt(R)*Estar_;
+
+        scalar etaN = alpha_*sqrt(M*kN)*pow(deltaN, 0.25);
+
+        vector normalForce = -(kN*pow(deltaN, b_) + etaN*(Urel & n))*n;
+
+        pA.f() += normalForce;
+        pB.f() -= normalForce;
+    }
+}
+
+
+// ************************************************************************* //
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.H b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.H
new file mode 100644
index 0000000000..b2f3316b25
--- /dev/null
+++ b/src/lagrangian/intermediate/submodels/Kinematic/CollisionModel/PairCollision/PairFunction/SpringSliderDashpot/SpringSliderDashpot.H
@@ -0,0 +1,112 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2008-2009 OpenCFD Ltd.
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software; you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by the
+    Free Software Foundation; either version 2 of the License, or (at your
+    option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+
+Class
+    Foam::SpringSliderDashpot
+
+Description
+    Pair forces between particles colliding with a spring, slider, damper model
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef SpringSliderDashpot_H
+#define SpringSliderDashpot_H
+
+#include "PairFunction.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+/*---------------------------------------------------------------------------*\
+                      Class SpringSliderDashpot Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class CloudType>
+class SpringSliderDashpot
+:
+    public PairFunction<CloudType>
+{
+    // Private data
+
+        //- Effective Young's modulus value, assuming both particles have
+        //  the same E value
+        scalar Estar_;
+
+        //- Effective shear modulus value, assuming both particles have
+        //  the same Poisson's ratio and Young's modulus
+        scalar Gstar_;
+
+        //- Poisson's ratio of both particles
+        scalar sigma_;
+
+        //- alpha-coefficient, related to coefficient of restitution
+        scalar alpha_;
+
+        //- Spring power (b = 1 for linear, b = 3/2 for Hertzian)
+        scalar b_;
+
+
+public:
+
+    //- Runtime type information
+    TypeName("SpringSliderDashpot");
+
+
+    // Constructors
+
+        //- Construct from dictionary
+        SpringSliderDashpot(const dictionary& dict, CloudType& cloud);
+
+
+    //- Destructor
+    virtual ~SpringSliderDashpot();
+
+
+    // Member Functions
+
+        //- Calculate the pair interaction between parcels
+        virtual void evaluatePair
+        (
+            typename CloudType::parcelType& pA,
+            typename CloudType::parcelType& pB
+        ) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+#   include "SpringSliderDashpot.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //