diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.C b/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.C
index 11843958d5..a6d7b44bb5 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.C
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.C
@@ -26,7 +26,6 @@ License
 
 #include "SpalartAllmaras.H"
 #include "addToRunTimeSelectionTable.H"
-#include "wallDist.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -54,7 +53,7 @@ tmp<volScalarField> SpalartAllmaras::fv1() const
 tmp<volScalarField> SpalartAllmaras::fv2() const
 {
     volScalarField chi = nuTilda_/nu();
-    return 1.0/pow3(scalar(1) + chi/Cv2_);
+    return 1/pow3(scalar(1) + chi/Cv2_);
 }
 
 
@@ -71,70 +70,68 @@ tmp<volScalarField> SpalartAllmaras::fv3() const
 }
 
 
-tmp<volScalarField> SpalartAllmaras::calcS(const volTensorField& gradU)
+tmp<volScalarField> SpalartAllmaras::S(const volTensorField& gradU) const
 {
-    return ::sqrt(2.0)*mag(skew(gradU));
+    return sqrt(2.0)*mag(skew(gradU));
 }
 
 
-tmp<volScalarField> SpalartAllmaras::calcSTilda(const volTensorField& gradU)
+tmp<volScalarField> SpalartAllmaras::STilda
+(
+    const volScalarField& S,
+    const volScalarField& dTilda
+) const
 {
-    return fv3()*calcS(gradU) + fv2()*nuTilda_/sqr(kappa_*dTilda_);
+    return fv3()*S + fv2()*nuTilda_/sqr(kappa_*dTilda);
 }
 
 
 tmp<volScalarField> SpalartAllmaras::r
 (
     const volScalarField& visc,
-    const volScalarField& S
+    const volScalarField& S,
+    const volScalarField& dTilda
 ) const
 {
-    tmp<volScalarField> tr
+    return min
     (
-        new volScalarField
-        (
-            min
-            (
-                visc
-               /(
-                    max
-                    (
-                        S,
-                        dimensionedScalar("SMALL", S.dimensions(), SMALL)
-                    )
-                   *sqr(kappa_*dTilda_)
-                  + dimensionedScalar
-                    (
-                        "ROOTVSMALL",
-                        dimensionSet(0, 2 , -1, 0, 0),
-                        ROOTVSMALL
-                    )
-                ),
-                scalar(10.0)
-            )
-        )
+        visc
+       /(
+           max
+           (
+               S,
+               dimensionedScalar("SMALL", S.dimensions(), SMALL)
+           )
+          *sqr(kappa_*dTilda)
+         + dimensionedScalar
+           (
+               "ROOTVSMALL",
+               dimensionSet(0, 2 , -1, 0, 0),
+               ROOTVSMALL
+           )
+        ),
+        scalar(10)
     );
-
-    return tr;
 }
 
 
-tmp<volScalarField> SpalartAllmaras::fw(const volScalarField& S) const
+tmp<volScalarField> SpalartAllmaras::fw
+(
+    const volScalarField& S,
+    const volScalarField& dTilda
+) const
 {
-    volScalarField r = this->r(nuTilda_, S);
+    volScalarField r = this->r(nuTilda_, S, dTilda);
 
     volScalarField g = r + Cw2_*(pow6(r) - r);
 
-    return g*pow((1.0 + pow6(Cw3_))/(pow6(g) + pow6(Cw3_)), 1.0/6.0);
+    return g*pow((1 + pow6(Cw3_))/(pow6(g) + pow6(Cw3_)), 1.0/6.0);
 }
 
 
-void SpalartAllmaras::dTildaUpdate(const volScalarField&)
+tmp<volScalarField> SpalartAllmaras::dTilda(const volScalarField&) const
 {
-    if (mesh_.changing())
-    {
-        dTilda_ = min(CDES_*delta(), wallDist(mesh_).y());
-    }
+    return min(CDES_*delta(), y_);
 }
 
 
@@ -242,6 +239,8 @@ SpalartAllmaras::SpalartAllmaras
         )
     ),
 
+    y_(mesh_),
+
     nuTilda_
     (
         IOobject
@@ -255,8 +254,6 @@ SpalartAllmaras::SpalartAllmaras
         mesh_
     ),
 
-    dTilda_(min(CDES_*delta(), wallDist(mesh_).y())),
-
     nuSgs_
     (
         IOobject
@@ -277,11 +274,15 @@ void SpalartAllmaras::correct(const tmp<volTensorField>& gradU)
 {
     LESModel::correct(gradU);
 
-    const volScalarField STilda = calcSTilda(gradU);
+    if (mesh_.changing())
+    {
+        y_.correct();
+        y_.boundaryField() = max(y_.boundaryField(), VSMALL);
+    }
 
-    const volScalarField S = calcS(gradU);
-
-    dTildaUpdate(S);
+    const volScalarField S = this->S(gradU);
+    const volScalarField dTilda = this->dTilda(S);
+    const volScalarField STilda = this->STilda(S, dTilda);
 
     fvScalarMatrix nuTildaEqn
     (
@@ -296,7 +297,7 @@ void SpalartAllmaras::correct(const tmp<volTensorField>& gradU)
       - alphaNut_*Cb2_*magSqr(fvc::grad(nuTilda_))
      ==
         Cb1_*STilda*nuTilda_
-      - fvm::Sp(Cw1_*fw(STilda)*nuTilda_/sqr(dTilda_), nuTilda_)
+      - fvm::Sp(Cw1_*fw(STilda, dTilda)*nuTilda_/sqr(dTilda), nuTilda_)
     );
 
     nuTildaEqn.relax();
@@ -310,9 +311,15 @@ void SpalartAllmaras::correct(const tmp<volTensorField>& gradU)
 }
 
 
+tmp<volScalarField> SpalartAllmaras::k() const
+{
+    return sqr(nuSgs()/ck_/dTilda(S(fvc::grad(U()))));
+}
+
+
 tmp<volScalarField> SpalartAllmaras::epsilon() const
 {
-    return 2.0*nuEff()*magSqr(symm(fvc::grad(U())));
+    return 2*nuEff()*magSqr(symm(fvc::grad(U())));
 }
 
 
diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.H b/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.H
index aa721b1b5c..b813075b1d 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.H
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmaras/SpalartAllmaras.H
@@ -38,6 +38,7 @@ SourceFiles
 
 #include "LESModel.H"
 #include "volFields.H"
+#include "wallDist.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -86,30 +87,39 @@ protected:
 
         // Fields
 
+            wallDist y_;
             volScalarField nuTilda_;
-            volScalarField dTilda_;
             volScalarField nuSgs_;
 
 
     // Protected member functions
 
-        // Helper functions
+        virtual tmp<volScalarField> fv1() const;
+        virtual tmp<volScalarField> fv2() const;
+        virtual tmp<volScalarField> fv3() const;
+        virtual tmp<volScalarField> S(const volTensorField& gradU) const;
 
-            virtual tmp<volScalarField> fv1() const;
-            virtual tmp<volScalarField> fv2() const;
-            virtual tmp<volScalarField> fv3() const;
-            //-
-            virtual tmp<volScalarField> calcS(const volTensorField& gradU);
-            virtual tmp<volScalarField> calcSTilda(const volTensorField& gradU);
-            virtual tmp<volScalarField> r
-            (
-                const volScalarField& visc,
-                const volScalarField& S
-            ) const;
-            virtual tmp<volScalarField> fw(const volScalarField& S) const;
+        virtual tmp<volScalarField> STilda
+        (
+            const volScalarField& S,
+            const volScalarField& dTilda
+        ) const;
 
-        //- Length scale calculation
-        virtual void dTildaUpdate(const volScalarField& S);
+        virtual tmp<volScalarField> r
+        (
+            const volScalarField& visc,
+            const volScalarField& S,
+            const volScalarField& dTilda
+        ) const;
+
+        virtual tmp<volScalarField> fw
+        (
+            const volScalarField& S,
+            const volScalarField& dTilda
+        ) const;
+
+        //- Length scale
+        virtual tmp<volScalarField> dTilda(const volScalarField& S) const;
 
 
 public:
@@ -138,10 +148,7 @@ public:
     // Member Functions
 
         //- Return SGS kinetic energy
-        virtual tmp<volScalarField> k() const
-        {
-            return sqr(nuSgs()/ck_/dTilda_);
-        }
+        virtual tmp<volScalarField> k() const;
 
         //- Return sub-grid disipation rate
         virtual tmp<volScalarField> epsilon() const;
diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.C b/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.C
index 6f5435a268..edba5b1d3c 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.C
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.C
@@ -26,7 +26,6 @@ License
 
 #include "SpalartAllmarasDDES.H"
 #include "addToRunTimeSelectionTable.H"
-#include "wallDist.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -50,51 +49,42 @@ tmp<volScalarField> SpalartAllmarasDDES::rd
     const volScalarField& S
 ) const
 {
-    volScalarField d = wallDist(mesh_).y();
-
-    tmp<volScalarField> trd
+    return min
     (
-        new volScalarField
-        (
-            min
+        visc
+        /(
+            max
             (
-                visc
-               /(
-                    max
-                    (
-                        S,
-                        dimensionedScalar("SMALL", S.dimensions(), SMALL)
-                    )*sqr(kappa_*d)
-                  + dimensionedScalar
-                    (
-                        "ROOTVSMALL",
-                        dimensionSet(0, 2 , -1, 0, 0),
-                        ROOTVSMALL
-                    )
-                ), scalar(10.0)
+                S,
+                dimensionedScalar("SMALL", S.dimensions(), SMALL)
+            )*sqr(kappa_*y_)
+          + dimensionedScalar
+            (
+                "ROOTVSMALL",
+                dimensionSet(0, 2 , -1, 0, 0),
+                ROOTVSMALL
             )
-        )
+        ),
+        scalar(10)
     );
-
-    return trd;
 }
 
 
-tmp<volScalarField> SpalartAllmarasDDES::fd(const volScalarField& S)
+tmp<volScalarField> SpalartAllmarasDDES::fd(const volScalarField& S) const
 {
-    return 1.0 - tanh(pow3(8.0*rd(nuSgs_ + transport().nu(), S)));
+    return 1 - tanh(pow3(8*rd(nuEff(), S)));
 }
 
 
-void SpalartAllmarasDDES::dTildaUpdate(const volScalarField& S)
+tmp<volScalarField> SpalartAllmarasDDES::dTilda(const volScalarField& S) const
 {
-    dTilda_ =
-        wallDist(mesh_).y()
-      - fd(S)*max
-        (
-            dimensionedScalar("zero", dimLength, 0.0),
-            wallDist(mesh_).y() - CDES_*delta()
-        );
+    return max
+    (
+        y_
+      - fd(S)
+       *max(y_ - CDES_*delta(), dimensionedScalar("zero", dimLength, 0)),
+        dimensionedScalar("small", dimLength, SMALL)
+    );
 }
 
 
diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.H b/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.H
index ec7eeda68c..52d7c99c6a 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.H
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmarasDDES/SpalartAllmarasDDES.H
@@ -62,6 +62,14 @@ class SpalartAllmarasDDES
 {
     // Private member functions
 
+        tmp<volScalarField> fd(const volScalarField& S) const;
+
+        tmp<volScalarField> rd
+        (
+            const volScalarField& visc,
+            const volScalarField& S
+        ) const;
+
         // Disallow default bitwise copy construct and assignment
         SpalartAllmarasDDES(const SpalartAllmarasDDES&);
         SpalartAllmarasDDES& operator=(const SpalartAllmarasDDES&);
@@ -71,15 +79,8 @@ protected:
 
     // Protected member functions
 
-        tmp<volScalarField> fd(const volScalarField& S);
-        tmp<volScalarField> rd
-        (
-            const volScalarField& visc,
-            const volScalarField& S
-        ) const;
-
-        //- Length scale calculation
-        virtual void dTildaUpdate(const volScalarField& S);
+        //- Length scale
+        virtual tmp<volScalarField> dTilda(const volScalarField& S) const;
 
 
 public:
diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.C b/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.C
index 6912872c9b..4fc7c02057 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.C
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.C
@@ -26,7 +26,6 @@ License
 
 #include "SpalartAllmarasIDDES.H"
 #include "addToRunTimeSelectionTable.H"
-#include "wallDist.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -46,22 +45,29 @@ addToRunTimeSelectionTable(LESModel, SpalartAllmarasIDDES, dictionary);
 
 tmp<volScalarField> SpalartAllmarasIDDES::alpha() const
 {
-    return
-        0.25
-      - wallDist(mesh_).y()
-       /dimensionedScalar("hMax", dimLength, max(cmptMax(delta())));
+    return max
+    (
+        0.25 - y_/dimensionedScalar("hMax", dimLength, max(cmptMax(delta()))),
+        scalar(-5)
+    );
 }
 
 
-tmp<volScalarField> SpalartAllmarasIDDES::ft(const volScalarField& S) const
+tmp<volScalarField> SpalartAllmarasIDDES::ft
+(
+    const volScalarField& S
+) const
 {
-    return tanh(pow3(sqr(ct_)*r(nuSgs_, S)));
+    return tanh(pow3(sqr(ct_)*rd(nuSgs_, S)));
 }
 
 
-tmp<volScalarField> SpalartAllmarasIDDES::fl(const volScalarField& S) const
+tmp<volScalarField> SpalartAllmarasIDDES::fl
+(
+    const volScalarField& S
+) const
 {
-    return tanh(pow(sqr(cl_)*r(transport().nu(), S), 10));
+    return tanh(pow(sqr(cl_)*rd(nu(), S), 10));
 }
 
 
@@ -71,33 +77,24 @@ tmp<volScalarField> SpalartAllmarasIDDES::rd
     const volScalarField& S
 ) const
 {
-    volScalarField d = wallDist(mesh_).y();
-
-    tmp<volScalarField> trd
+    return min
     (
-        new volScalarField
-        (
-            min
-            (
-                visc
-               /(
-                   max
-                   (
-                       S,
-                       dimensionedScalar("SMALL", S.dimensions(), SMALL)
-                   )*sqr(kappa_*d)
-                 + dimensionedScalar
-                   (
-                       "ROOTVSMALL",
-                       dimensionSet(0, 2 , -1, 0, 0),
-                       ROOTVSMALL
-                   )
-               ), scalar(10.0)
-            )
-        )
+        visc
+       /(
+           max
+           (
+               S,
+               dimensionedScalar("SMALL", S.dimensions(), SMALL)
+           )*sqr(kappa_*y_)
+         + dimensionedScalar
+           (
+               "ROOTVSMALL",
+               dimensionSet(0, 2 , -1, 0, 0),
+               ROOTVSMALL
+           )
+       ),
+       scalar(10)
     );
-
-    return trd;
 }
 
 
@@ -105,43 +102,38 @@ tmp<volScalarField> SpalartAllmarasIDDES::rd
 
 tmp<volScalarField> SpalartAllmarasIDDES::fd(const volScalarField& S) const
 {
-    return 1.0 - tanh(pow3(8.0*rd(nuSgs_+transport().nu(), S)));
+    return 1 - tanh(pow3(8*rd(nuEff(), S)));
 }
 
 
-void SpalartAllmarasIDDES::dTildaUpdate(const volScalarField& S)
+tmp<volScalarField> SpalartAllmarasIDDES::dTilda(const volScalarField& S) const
 {
     volScalarField alpha = this->alpha();
-
     volScalarField expTerm = exp(sqr(alpha));
 
     volScalarField fHill =
-        2.0*(pos(alpha)*pow(expTerm, -11.09) + neg(alpha)*pow(expTerm, -9.0));
+        2*(pos(alpha)*pow(expTerm, -11.09) + neg(alpha)*pow(expTerm, -9.0));
 
+    volScalarField fStep = min(2*pow(expTerm, -9.0), scalar(1));
+    volScalarField fHyb = max(1 - fd(S), fStep);
+    volScalarField fAmp = 1 - max(ft(S), fl(S));
+    volScalarField fRestore = max(fHill - 1, scalar(0))*fAmp;
 
-    volScalarField fStep = min(2.0*pow(expTerm, -9.0), scalar(1));
-    volScalarField fHyb = max(1.0 - fd(S), fStep);
-
-    volScalarField fAmp = 1.0 - max(ft(S), fl(S));
-
-    volScalarField fRestore = max(fHill - 1.0, scalar(0))*fAmp;
-
-    // volScalarField ft2 = IGNORING ft2 terms
-
+    // IGNORING ft2 terms
     volScalarField Psi = sqrt
     (
         min
         (
             scalar(100),
-            (1.0 - Cb1_/(Cw1_*sqr(kappa_)*fwStar_)*fv2())/max(SMALL, fv1())
+            (1 - Cb1_/(Cw1_*sqr(kappa_)*fwStar_)*fv2())/max(SMALL, fv1())
         )
     );
 
-    dTilda_ = max
+    return max
     (
-        dimensionedScalar("zero", dimLength, 0.0),
-        fHyb*(1.0 + fRestore*Psi)*wallDist(mesh_).y()
-      + (1.0 - fHyb)*CDES_*Psi*delta()
+        dimensionedScalar("SMALL", dimLength, SMALL),
+        fHyb*(1 + fRestore*Psi)*y_
+      + (1 - fHyb)*CDES_*Psi*delta()
     );
 }
 
diff --git a/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.H b/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.H
index 815d2c28a6..8c7ca63ceb 100644
--- a/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.H
+++ b/src/turbulenceModels/incompressible/LES/SpalartAllmarasIDDES/SpalartAllmarasIDDES.H
@@ -69,12 +69,16 @@ class SpalartAllmarasIDDES
         tmp<volScalarField> alpha() const;
         tmp<volScalarField> ft(const volScalarField& S) const;
         tmp<volScalarField> fl(const volScalarField& S) const;
+
         tmp<volScalarField> rd
         (
             const volScalarField& visc,
             const volScalarField& S
         ) const;
 
+        //- Delay function
+        tmp<volScalarField> fd(const volScalarField& S) const;
+
         // Disallow default bitwise copy construct and assignment
         SpalartAllmarasIDDES(const SpalartAllmarasIDDES&);
         SpalartAllmarasIDDES& operator=(const SpalartAllmarasIDDES&);
@@ -84,11 +88,9 @@ protected:
 
     // Protected member functions
 
-        //- Delay function
-        tmp<volScalarField> fd(const volScalarField& S) const;
+        //- Length scale
+        virtual tmp<volScalarField> dTilda(const volScalarField& S) const;
 
-        //- Length scale calculation
-        virtual void dTildaUpdate(const volScalarField& S);
 
 public: