diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.C
index b5e7d162db..946564c1b8 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.C
@@ -37,21 +37,23 @@ Foam::LocalInteraction<CloudType>::LocalInteraction
     PatchInteractionModel<CloudType>(dict, cloud, typeName),
     patchData_(cloud.mesh(), this->coeffDict()),
     nEscape_(patchData_.size()),
-    massEscape_(patchData_.size()),
-    nStick_(patchData_.size()),
-    massStick_(patchData_.size()),
+    massEscape_(nEscape_.size()),
+    nStick_(nEscape_.size()),
+    massStick_(nEscape_.size()),
     writeFields_(this->coeffDict().lookupOrDefault("writeFields", false)),
-    outputByInjectorId_(this->coeffDict().lookupOrDefault("outputByInjectorId", false)),
-    injIdToIndex_(cloud.injectors().size()),
+    injIdToIndex_(),
     massEscapePtr_(nullptr),
     massStickPtr_(nullptr)
 {
+    const bool outputByInjectorId
+        = this->coeffDict().lookupOrDefault("outputByInjectorId", false);
+
     if (writeFields_)
     {
-        word massEscapeName(this->owner().name() + ":massEscape");
-        word massStickName(this->owner().name() + ":massStick");
-        Info<< "    Interaction fields will be written to " << massEscapeName
-            << " and " << massStickName << endl;
+        Info<< "    Interaction fields will be written to "
+            << this->owner().name() << ":massEscape"
+            << " and "
+            << this->owner().name() << ":massStick" << endl;
 
         (void)massEscape();
         (void)massStick();
@@ -61,7 +63,23 @@ Foam::LocalInteraction<CloudType>::LocalInteraction
         Info<< "    Interaction fields will not be written" << endl;
     }
 
-    // check that interactions are valid/specified
+    // Determine the number of injectors and the injector mapping
+    label nInjectors = 0;
+    if (outputByInjectorId)
+    {
+        for (const auto& inj : cloud.injectors())
+        {
+            injIdToIndex_.insert(inj.injectorID(), nInjectors++);
+        }
+    }
+
+    // The normal case, and safety if injector mapping was somehow null.
+    if (!nInjectors)
+    {
+        nInjectors = 1;
+    }
+
+    // Check that interactions are valid/specified
     forAll(patchData_, patchi)
     {
         const word& interactionTypeName =
@@ -80,20 +98,10 @@ Foam::LocalInteraction<CloudType>::LocalInteraction
                 << nl << exit(FatalError);
         }
 
-        label nInjectors(1);
-        if (outputByInjectorId_)
-        {
-            nInjectors = cloud.injectors().size();
-            for (label i=0; i<nInjectors; i++)
-            {
-                injIdToIndex_.insert(cloud.injectors()[i].injectorID(), i);
-            }
-        }
-
-        nEscape_[patchi].setSize(nInjectors, 0);
-        massEscape_[patchi].setSize(nInjectors, 0.0);
-        nStick_[patchi].setSize(nInjectors, 0);
-        massStick_[patchi].setSize(nInjectors, 0.0);
+        nEscape_[patchi].setSize(nInjectors, Zero);
+        massEscape_[patchi].setSize(nInjectors, Zero);
+        nStick_[patchi].setSize(nInjectors, Zero);
+        massStick_[patchi].setSize(nInjectors, Zero);
     }
 }
 
@@ -111,20 +119,12 @@ Foam::LocalInteraction<CloudType>::LocalInteraction
     nStick_(pim.nStick_),
     massStick_(pim.massStick_),
     writeFields_(pim.writeFields_),
-    outputByInjectorId_(pim.outputByInjectorId_),
     injIdToIndex_(pim.injIdToIndex_),
     massEscapePtr_(nullptr),
     massStickPtr_(nullptr)
 {}
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-template<class CloudType>
-Foam::LocalInteraction<CloudType>::~LocalInteraction()
-{}
-
-
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
 template<class CloudType>
@@ -193,12 +193,20 @@ bool Foam::LocalInteraction<CloudType>::correct
     bool& keepParticle
 )
 {
-    label patchi = patchData_.applyToPatch(pp.index());
+    const label patchi = patchData_.applyToPatch(pp.index());
 
     if (patchi >= 0)
     {
         vector& U = p.U();
 
+        // Location for storing the stats.
+        const label idx =
+        (
+            injIdToIndex_.size()
+          ? injIdToIndex_.lookup(p.typeId(), 0)
+          : 0
+        );
+
         typename PatchInteractionModel<CloudType>::interactionType it =
             this->wordToInteractionType
             (
@@ -213,50 +221,38 @@ bool Foam::LocalInteraction<CloudType>::correct
             }
             case PatchInteractionModel<CloudType>::itEscape:
             {
-                scalar dm = p.mass()*p.nParticle();
-
                 keepParticle = false;
                 p.active(false);
                 U = Zero;
-                if (outputByInjectorId_)
-                {
-                    nEscape_[patchi][injIdToIndex_[p.typeId()]]++;
-                    massEscape_[patchi][injIdToIndex_[p.typeId()]] += dm;
-                }
-                else
-                {
-                    nEscape_[patchi][0]++;
-                    massEscape_[patchi][0] += dm;
-                }
+
+                const scalar dm = p.mass()*p.nParticle();
+
+                nEscape_[patchi][idx]++;
+                massEscape_[patchi][idx] += dm;
+
                 if (writeFields_)
                 {
-                    label pI = pp.index();
-                    label fI = pp.whichFace(p.face());
+                    const label pI = pp.index();
+                    const label fI = pp.whichFace(p.face());
                     massEscape().boundaryFieldRef()[pI][fI] += dm;
                 }
                 break;
             }
             case PatchInteractionModel<CloudType>::itStick:
             {
-                scalar dm = p.mass()*p.nParticle();
-
                 keepParticle = true;
                 p.active(false);
                 U = Zero;
-                if (outputByInjectorId_)
-                {
-                    nStick_[patchi][injIdToIndex_[p.typeId()]]++;
-                    massStick_[patchi][injIdToIndex_[p.typeId()]] += dm;
-                }
-                else
-                {
-                    nStick_[patchi][0]++;
-                    massStick_[patchi][0] += dm;
-                }
+
+                const scalar dm = p.mass()*p.nParticle();
+
+                nStick_[patchi][idx]++;
+                massStick_[patchi][idx] += dm;
+
                 if (writeFields_)
                 {
-                    label pI = pp.index();
-                    label fI = pp.whichFace(p.face());
+                    const label pI = pp.index();
+                    const label fI = pp.whichFace(p.face());
                     massStick().boundaryFieldRef()[pI][fI] += dm;
                 }
                 break;
@@ -355,21 +351,28 @@ void Foam::LocalInteraction<CloudType>::info(Ostream& os)
         mps[i] = mps[i] + mps0[i];
     }
 
-
-    if (outputByInjectorId_)
+    if (injIdToIndex_.size())
     {
+        // Since injIdToIndex_ is a one-to-one mapping (starting as zero),
+        // can simply invert it.
+        labelList indexToInjector(injIdToIndex_.size());
+        forAllConstIters(injIdToIndex_, iter)
+        {
+            indexToInjector[iter.object()] = iter.key();
+        }
+
         forAll(patchData_, i)
         {
-            forAll (mpe[i], injId)
+            forAll(mpe[i], idx)
             {
                 os  << "    Parcel fate: patch " <<  patchData_[i].patchName()
                     << " (number, mass)" << nl
-                    << "      - escape  (injector " << injIdToIndex_.toc()[injId]
-                    << " )  = " << npe[i][injId]
-                    << ", " << mpe[i][injId] << nl
-                    << "      - stick   (injector " << injIdToIndex_.toc()[injId]
-                    << " )  = " << nps[i][injId]
-                    << ", " << mps[i][injId] << nl;
+                    << "      - escape  (injector " << indexToInjector[idx]
+                    << " )  = " << npe[i][idx]
+                    << ", " << mpe[i][idx] << nl
+                    << "      - stick   (injector " << indexToInjector[idx]
+                    << " )  = " << nps[i][idx]
+                    << ", " << mps[i][idx] << nl;
             }
         }
     }
@@ -379,25 +382,23 @@ void Foam::LocalInteraction<CloudType>::info(Ostream& os)
         {
             os  << "    Parcel fate: patch " <<  patchData_[i].patchName()
                 << " (number, mass)" << nl
-                << "      - escape                      = " << npe[i][0]
-                << ", " << mpe[i][0] << nl
-                << "      - stick                       = " << nps[i][0]
-                << ", " << mps[i][0] << nl;
+                << "      - escape                      = "
+                << npe[i][0] << ", " << mpe[i][0] << nl
+                << "      - stick                       = "
+                << nps[i][0] << ", " << mps[i][0] << nl;
         }
     }
 
     if (this->writeTime())
     {
         this->setModelProperty("nEscape", npe);
-        nEscape_ = Zero;
-
         this->setModelProperty("massEscape", mpe);
-        massEscape_ = Zero;
-
         this->setModelProperty("nStick", nps);
-        nStick_ = Zero;
-
         this->setModelProperty("massStick", mps);
+
+        nEscape_ = Zero;
+        massEscape_ = Zero;
+        nStick_ = Zero;
         massStick_ = Zero;
     }
 }
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.H
index 693389c1b4..72b00ffb98 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/LocalInteraction/LocalInteraction.H
@@ -43,6 +43,7 @@ Description
 
 namespace Foam
 {
+
 /*---------------------------------------------------------------------------*\
                       Class LocalInteraction Declaration
 \*---------------------------------------------------------------------------*/
@@ -57,29 +58,25 @@ class LocalInteraction
         //- List of participating patches
         const patchInteractionDataList patchData_;
 
+    // Bookkeeping for particle fates
 
-        // Counters for particle fates
+        //- Number of parcels escaped
+        List<List<label>> nEscape_;
 
-            //- Number of parcels escaped
-            List<List<label>> nEscape_;
+        //- Mass of parcels escaped
+        List<List<scalar>> massEscape_;
 
-            //- Mass of parcels escaped
-            List<List<scalar>> massEscape_;
-
-            //- Number of parcels stuck to patches
-            List<List<label>> nStick_;
-
-            //- Mass of parcels stuck to patches
-            List<List<scalar>> massStick_;
+        //- Number of parcels stuck to patches
+        List<List<label>> nStick_;
 
+        //- Mass of parcels stuck to patches
+        List<List<scalar>> massStick_;
 
         //- Flag to output data as fields
-        Switch writeFields_;
+        bool writeFields_;
 
-        //- Flag to output escaped/mass particles sorted by injectorID
-        Switch outputByInjectorId_;
-
-        //- InjectorId to index map
+        //- InjectorId to index map, when outputting escaped/stick/...
+        //  particles sorted by injectorID
         Map<label> injIdToIndex_;
 
         //- Mass escape field
@@ -115,7 +112,7 @@ public:
 
 
     //- Destructor
-    virtual ~LocalInteraction();
+    virtual ~LocalInteraction() = default;
 
 
     // Member Functions
@@ -136,10 +133,8 @@ public:
         );
 
 
-        // I-O
-
-            //- Write patch interaction info to stream
-            virtual void info(Ostream& os);
+        //- Write patch interaction info to stream
+        virtual void info(Ostream& os);
 };
 
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.C
index bdd8a542c8..65b884b9b3 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.C
@@ -108,13 +108,6 @@ Foam::MultiInteraction<CloudType>::MultiInteraction
 {}
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-template<class CloudType>
-Foam::MultiInteraction<CloudType>::~MultiInteraction()
-{}
-
-
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
 template<class CloudType>
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.H
index f3509baffc..f53c97b7d6 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/MultiInteraction/MultiInteraction.H
@@ -130,7 +130,7 @@ public:
 
 
     //- Destructor
-    virtual ~MultiInteraction();
+    virtual ~MultiInteraction() = default;
 
 
     // Member Functions
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.C
index 201dd0656d..525efd0427 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.C
@@ -48,13 +48,6 @@ Foam::NoInteraction<CloudType>::NoInteraction
 {}
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-template<class CloudType>
-Foam::NoInteraction<CloudType>::~NoInteraction()
-{}
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class CloudType>
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.H
index bad7641e93..1cf71edece 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/NoInteraction/NoInteraction.H
@@ -76,7 +76,7 @@ public:
 
 
     //- Destructor
-    virtual ~NoInteraction();
+    virtual ~NoInteraction() = default;
 
 
     // Member Functions
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.C
index c6af1d2378..d680dd891e 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.C
@@ -151,13 +151,6 @@ Foam::PatchInteractionModel<CloudType>::PatchInteractionModel
 {}
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-template<class CloudType>
-Foam::PatchInteractionModel<CloudType>::~PatchInteractionModel()
-{}
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class CloudType>
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.H
index bf33d941d7..8c7c7d4fc4 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/PatchInteractionModel/PatchInteractionModel.H
@@ -136,7 +136,7 @@ public:
 
 
     //- Destructor
-    virtual ~PatchInteractionModel();
+    virtual ~PatchInteractionModel() = default;
 
 
     //- Selector
@@ -174,10 +174,8 @@ public:
         void addToEscapedParcels(const scalar mass);
 
 
-        // I-O
-
-            //- Write patch interaction info to stream
-            virtual void info(Ostream& os);
+        //- Write patch interaction info to stream
+        virtual void info(Ostream& os);
 };
 
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.C
index 9c617059ac..0b68d08f07 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.C
@@ -47,13 +47,6 @@ Foam::Rebound<CloudType>::Rebound(const Rebound<CloudType>& pim)
 {}
 
 
-// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
-
-template<class CloudType>
-Foam::Rebound<CloudType>::~Rebound()
-{}
-
-
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 template<class CloudType>
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.H
index d179f818e4..61d6fe11c6 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/Rebound/Rebound.H
@@ -82,10 +82,11 @@ public:
 
 
     //- Destructor
-    virtual ~Rebound();
+    virtual ~Rebound() = default;
 
 
     // Member Functions
+
         //- Apply velocity correction
         //  Returns true if particle remains in same cell
         virtual bool correct
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.C b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.C
index 186ce67958..03728eaee6 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.C
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.C
@@ -46,12 +46,11 @@ Foam::StandardWallInteraction<CloudType>::StandardWallInteraction
     massEscape_(nEscape_.size()),
     nStick_(nEscape_.size()),
     massStick_(nEscape_.size()),
-    outputByInjectorId_
-    (
-        this->coeffDict().lookupOrDefault("outputByInjectorId", false)
-    ),
-    injIdToIndex_(cloud.injectors().size())
+    injIdToIndex_()
 {
+    const bool outputByInjectorId
+        = this->coeffDict().lookupOrDefault("outputByInjectorId", false);
+
     switch (interactionType_)
     {
         case PatchInteractionModel<CloudType>::itOther:
@@ -76,22 +75,28 @@ Foam::StandardWallInteraction<CloudType>::StandardWallInteraction
         {}
     }
 
+    // Determine the number of injectors and the injector mapping
+    label nInjectors = 0;
+    if (outputByInjectorId)
+    {
+        for (const auto& inj : cloud.injectors())
+        {
+            injIdToIndex_.insert(inj.injectorID(), nInjectors++);
+        }
+    }
+
+    // The normal case, and safety if injector mapping was somehow null.
+    if (injIdToIndex_.empty())
+    {
+        nInjectors = 1;
+    }
+
     forAll(nEscape_, patchi)
     {
-        label nInjectors(1);
-        if (outputByInjectorId_)
-        {
-            nInjectors = cloud.injectors().size();
-            for (label i=0; i<nInjectors; i++)
-            {
-                injIdToIndex_.insert(cloud.injectors()[i].injectorID(), i);
-            }
-        }
-
-        nEscape_[patchi].setSize(nInjectors, 0);
-        massEscape_[patchi].setSize(nInjectors, 0.0);
-        nStick_[patchi].setSize(nInjectors, 0);
-        massStick_[patchi].setSize(nInjectors, 0.0);
+        nEscape_[patchi].setSize(nInjectors, Zero);
+        massEscape_[patchi].setSize(nInjectors, Zero);
+        nStick_[patchi].setSize(nInjectors, Zero);
+        massStick_[patchi].setSize(nInjectors, Zero);
     }
 }
 
@@ -111,7 +116,6 @@ Foam::StandardWallInteraction<CloudType>::StandardWallInteraction
     massEscape_(pim.massEscape_),
     nStick_(pim.nStick_),
     massStick_(pim.massStick_),
-    outputByInjectorId_(pim.outputByInjectorId_),
     injIdToIndex_(pim.injIdToIndex_)
 {}
 
@@ -130,6 +134,14 @@ bool Foam::StandardWallInteraction<CloudType>::correct
 
     if (isA<wallPolyPatch>(pp))
     {
+        // Location for storing the stats.
+        const label idx =
+        (
+            injIdToIndex_.size()
+          ? injIdToIndex_.lookup(p.typeId(), 0)
+          : 0
+        );
+
         switch (interactionType_)
         {
             case PatchInteractionModel<CloudType>::itNone:
@@ -141,17 +153,11 @@ bool Foam::StandardWallInteraction<CloudType>::correct
                 keepParticle = false;
                 p.active(false);
                 U = Zero;
+
                 const scalar dm = p.nParticle()*p.mass();
-                if (outputByInjectorId_)
-                {
-                    nEscape_[pp.index()][injIdToIndex_[p.typeId()]]++;
-                    massEscape_[pp.index()][injIdToIndex_[p.typeId()]] += dm;
-                }
-                else
-                {
-                    nEscape_[pp.index()][0]++;
-                    massEscape_[pp.index()][0] += dm;
-                }
+
+                nEscape_[pp.index()][idx]++;
+                massEscape_[pp.index()][idx] += dm;
                 break;
             }
             case PatchInteractionModel<CloudType>::itStick:
@@ -159,17 +165,11 @@ bool Foam::StandardWallInteraction<CloudType>::correct
                 keepParticle = true;
                 p.active(false);
                 U = Zero;
+
                 const scalar dm = p.nParticle()*p.mass();
-                if (outputByInjectorId_)
-                {
-                    nStick_[pp.index()][injIdToIndex_[p.typeId()]]++;
-                    massStick_[pp.index()][injIdToIndex_[p.typeId()]] += dm;
-                }
-                else
-                {
-                    nStick_[pp.index()][0]++;
-                    massStick_[pp.index()][0] += dm;
-                }
+
+                nStick_[pp.index()][idx]++;
+                massStick_[pp.index()][idx] += dm;
                 break;
             }
             case PatchInteractionModel<CloudType>::itRebound:
@@ -234,7 +234,7 @@ void Foam::StandardWallInteraction<CloudType>::info(Ostream& os)
     scalarListList mps0(massStick_);
     this->getModelProperty("massStick", mps0);
 
-    // accumulate current data
+    // Accumulate current data
     labelListList npe(nEscape_);
 
     forAll(npe, i)
@@ -264,20 +264,28 @@ void Foam::StandardWallInteraction<CloudType>::info(Ostream& os)
         mps[i] = mps[i] + mps0[i];
     }
 
-    if (outputByInjectorId_)
+    if (injIdToIndex_.size())
     {
+        // Since injIdToIndex_ is a one-to-one mapping (starting as zero),
+        // can simply invert it.
+        labelList indexToInjector(injIdToIndex_.size());
+        forAllConstIters(injIdToIndex_, iter)
+        {
+            indexToInjector[iter.object()] = iter.key();
+        }
+
         forAll(npe, i)
         {
-            forAll (mpe[i], injId)
+            forAll(mpe[i], idx)
             {
                 os  << "    Parcel fate: patch " <<  mesh_.boundary()[i].name()
                     << " (number, mass)" << nl
-                    << "      - escape  (injector " << injIdToIndex_.toc()[injId]
-                    << " )  = " << npe[i][injId]
-                    << ", " << mpe[i][injId] << nl
-                    << "      - stick   (injector " << injIdToIndex_.toc()[injId]
-                    << " )  = " << nps[i][injId]
-                    << ", " << mps[i][injId] << nl;
+                    << "      - escape  (injector " << indexToInjector[idx]
+                    << ")  = " << npe[i][idx]
+                    << ", " << mpe[i][idx] << nl
+                    << "      - stick   (injector " << indexToInjector[idx]
+                    << ")  = " << nps[i][idx]
+                    << ", " << mps[i][idx] << nl;
             }
         }
     }
@@ -285,7 +293,6 @@ void Foam::StandardWallInteraction<CloudType>::info(Ostream& os)
     {
         forAll(npe, i)
         {
-
             os  << "    Parcel fate: patch (number, mass) "
                 << mesh_.boundary()[i].name() << nl
                 << "      - escape                      = "
@@ -299,15 +306,15 @@ void Foam::StandardWallInteraction<CloudType>::info(Ostream& os)
     if (this->writeTime())
     {
         this->setModelProperty("nEscape", npe);
-        nEscape_ = Zero;
         this->setModelProperty("massEscape", mpe);
-        massEscape_ = Zero;
         this->setModelProperty("nStick", nps);
-        nStick_ = Zero;
         this->setModelProperty("massStick", mps);
+
+        nEscape_ = Zero;
+        massEscape_ = Zero;
+        nStick_ = Zero;
         massStick_ = Zero;
     }
-
 }
 
 
diff --git a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.H b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.H
index 35f09afd9e..7a32f641ff 100644
--- a/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.H
+++ b/src/lagrangian/intermediate/submodels/Kinematic/PatchInteractionModel/StandardWallInteraction/StandardWallInteraction.H
@@ -82,26 +82,26 @@ protected:
         //- Restitution coefficient
         scalar mu_;
 
+    // Bookkeeping for particle fates
 
-        // Counters for particle fates
+        //- Number of parcels escaped
+        List<List<label>> nEscape_;
 
-            //- Number of parcels escaped
-            List<List<label>> nEscape_;
+        //- Mass of parcels escaped
+        List<List<scalar>> massEscape_;
 
-            //- Mass of parcels escaped
-            List<List<scalar>> massEscape_;
+        //- Number of parcels stuck to patches
+        List<List<label>> nStick_;
 
-            //- Number of parcels stuck to patches
-            List<List<label>> nStick_;
+        //- Mass of parcels stuck to patches
+        List<List<scalar>> massStick_;
 
-            //- Mass of parcels stuck to patches
-            List<List<scalar>> massStick_;
+        //- Flag to output escaped/mass particles sorted by injectorID
+        bool outputByInjectorId_;
 
-            //- Flag to output escaped/mass particles sorted by injectorID
-            bool outputByInjectorId_;
-
-            //- InjectorId to index map
-            Map<label> injIdToIndex_;
+        //- InjectorId to index map, when outputting escaped/stick/...
+        //  particles sorted by injectorID
+        Map<label> injIdToIndex_;
 
 
 public:
@@ -144,10 +144,8 @@ public:
         );
 
 
-        // I-O
-
-            //- Write patch interaction info to stream
-            virtual void info(Ostream& os);
+        //- Write patch interaction info to stream
+        virtual void info(Ostream& os);
 };
 
 
diff --git a/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/Allrun-parallel b/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/Allrun-parallel
new file mode 100755
index 0000000000..b97529d442
--- /dev/null
+++ b/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/Allrun-parallel
@@ -0,0 +1,18 @@
+#!/bin/sh
+cd ${0%/*} || exit 1                        # Run from this directory
+. $WM_PROJECT_DIR/bin/tools/RunFunctions    # Tutorial run functions
+
+restore0Dir
+
+runApplication blockMesh
+
+runApplication potentialFoam
+
+# Remove incompatible (volumetric) flux field
+\rm -f 0/phi 2>/dev/null
+
+runApplication decomposePar
+
+runParallel $(getApplication)
+
+#------------------------------------------------------------------------------
diff --git a/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/system/decomposeParDict b/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/system/decomposeParDict
new file mode 100644
index 0000000000..d731400f85
--- /dev/null
+++ b/tutorials/lagrangian/simpleReactingParcelFoam/verticalChannel/system/decomposeParDict
@@ -0,0 +1,30 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  plus                                  |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    object      decomposeParDict;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+numberOfSubdomains 4;
+
+method          scotch;
+
+coeffs
+{
+    n           (2 2 1);
+}
+
+distributed     no;
+
+roots           ( );
+
+// ************************************************************************* //