diff --git a/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.C b/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.C
index 44769666..43a77955 100644
--- a/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.C
+++ b/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.C
@@ -54,7 +54,7 @@ void Foam::clockModel::start(int pos) const
     return;
 }
 
-void Foam::clockModel::start(int pos,std::string ident) const
+void Foam::clockModel::start(int pos, const std::string& ident) const
 {
     if (particleCloud_.mesh().time().value() > startTime_)
     {
@@ -96,7 +96,7 @@ void Foam::clockModel::stop() const
     return;
 }
 
-void Foam::clockModel::stop(std::string ident) const
+void Foam::clockModel::stop(const std::string& ident) const
 {
     if (particleCloud_.mesh().time().value() > startTime_)
     {
@@ -303,7 +303,7 @@ void Foam::clockModel::normHist() const
     return;
 }
 
-void Foam::clockModel::plotHist(double buffIn,std::string identifier,int numprocs,int myrank) const
+void Foam::clockModel::plotHist(double buffIn,const std::string& identifier,int numprocs,int myrank) const
 {
     double* globalTime_all = NULL;
     if (myrank == 0) globalTime_all = new double[numprocs];
diff --git a/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.H b/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.H
index 68d7bcde..942eae1b 100644
--- a/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.H
+++ b/src/lagrangian/cfdemParticle/subModels/clockModel/clockModel/clockModel.H
@@ -120,19 +120,19 @@ public:
 
     // Member Functions
 
-	    virtual void start(int pos) const;	                //start measurement with custom string identifier
-	    virtual void start(int pos,std::string identifier) const;   //start measurement with custom string identifier
-	    virtual void stop() const;				            //stop last started measurement
-	    virtual void stop(std::string identifier) const;    //stop last started measurement with check if identifier is equal
-	    virtual std::string eval() const;
-	    virtual void evalFile() const;
-	    virtual void evalPar() const;
-	    void initElems();
-	    std::vector<int> calcShift() const;			        //detects empty indices in vector, when times are evaluated
-	    void Hist() const;					                //calc Histogram
-	    virtual void normHist() const;				        //calc normalized Histogram
-        void plotHist(double,std::string,int,int) const;    //plot histogramm to terminal
-    	void getRAMUsage() const;
+        virtual void start(int pos) const;                  //start measurement with custom string identifier
+        virtual void start(int pos,const std::string& identifier) const;   //start measurement with custom string identifier
+        virtual void stop() const;                          //stop last started measurement
+        virtual void stop(const std::string& identifier) const;    //stop last started measurement with check if identifier is equal
+        virtual std::string eval() const;
+        virtual void evalFile() const;
+        virtual void evalPar() const;
+        void initElems();
+        std::vector<int> calcShift() const;	                //detects empty indices in vector, when times are evaluated
+        void Hist() const;                                  //calc Histogram
+        virtual void normHist() const;                      //calc normalized Histogram
+        void plotHist(double,const std::string&,int,int) const;    //plot histogramm to terminal
+        void getRAMUsage() const;
 
 };
 
diff --git a/src/lagrangian/cfdemParticle/subModels/clockModel/noClock/noClock.H b/src/lagrangian/cfdemParticle/subModels/clockModel/noClock/noClock.H
index dc89ad22..7af54865 100644
--- a/src/lagrangian/cfdemParticle/subModels/clockModel/noClock/noClock.H
+++ b/src/lagrangian/cfdemParticle/subModels/clockModel/noClock/noClock.H
@@ -77,14 +77,14 @@ public:
 
     // Member Functions
 
-	    void start(int pos) const {};
-	    void start(int pos,std::string identifier) const {};
-	    void stop() const {};
-	    void stop(std::string identifier) const {};
-	    std::string eval() const {return "";};
-	    void evalFile() const {};
-	    void evalPar() const {};
-        void normHist() const {};
+        void start(int pos) const {}
+        void start(int pos,const std::string& identifier) const {}
+        void stop() const {}
+        void stop(const std::string& identifier) const {}
+        std::string eval() const { return ""; }
+        void evalFile() const {}
+        void evalPar() const {}
+        void normHist() const {}
 };