diff --git a/applications/solvers/multiphase/reactingEulerFoam/interfacialModels/dragModels/segregated/segregated.C b/applications/solvers/multiphase/reactingEulerFoam/interfacialModels/dragModels/segregated/segregated.C
index dc122a0951..0f93b592f5 100644
--- a/applications/solvers/multiphase/reactingEulerFoam/interfacialModels/dragModels/segregated/segregated.C
+++ b/applications/solvers/multiphase/reactingEulerFoam/interfacialModels/dragModels/segregated/segregated.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -107,7 +107,7 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
     L.primitiveFieldRef() = cbrt(mesh.V());
     L.correctBoundaryConditions();
 
-    volScalarField I
+    const volScalarField I
     (
         alpha1
        /max
@@ -116,7 +116,8 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
             pair_.phase1().residualAlpha() + pair_.phase2().residualAlpha()
         )
     );
-    volScalarField magGradI
+
+    const volScalarField magGradI
     (
         max
         (
@@ -125,28 +126,35 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
         )
     );
 
-    volScalarField muI
+    const volScalarField muI
     (
         rho1*nu1*rho2*nu2
        /(rho1*nu1 + rho2*nu2)
     );
-    volScalarField muAlphaI
+
+    const volScalarField limitedAlpha1
+    (
+        max(alpha1, pair_.phase1().residualAlpha())
+    );
+
+    const volScalarField limitedAlpha2
+    (
+        max(alpha2, pair_.phase2().residualAlpha())
+    );
+
+    const volScalarField muAlphaI
     (
         alpha1*rho1*nu1*alpha2*rho2*nu2
-       /(
-           max(alpha1, pair_.phase1().residualAlpha())*rho1*nu1
-         + max(alpha2, pair_.phase2().residualAlpha())*rho2*nu2
-        )
+       /(limitedAlpha1*rho1*nu1 + limitedAlpha2*rho2*nu2)
     );
 
-    volScalarField ReI
+    const volScalarField ReI
     (
-        pair_.rho()
-       *pair_.magUr()
-       /(magGradI*muI)
+        pair_.rho()*pair_.magUr()
+       /(magGradI*limitedAlpha1*limitedAlpha2*muI)
     );
 
-    volScalarField lambda(m_*ReI + n_*muAlphaI/muI);
+    const volScalarField lambda(m_*ReI + n_*muAlphaI/muI);
 
     return lambda*sqr(magGradI)*muI;
 }
diff --git a/applications/solvers/multiphase/twoPhaseEulerFoam/interfacialModels/dragModels/segregated/segregated.C b/applications/solvers/multiphase/twoPhaseEulerFoam/interfacialModels/dragModels/segregated/segregated.C
index d4996cbbc7..3c2666fe07 100644
--- a/applications/solvers/multiphase/twoPhaseEulerFoam/interfacialModels/dragModels/segregated/segregated.C
+++ b/applications/solvers/multiphase/twoPhaseEulerFoam/interfacialModels/dragModels/segregated/segregated.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2014-2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2014-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -107,7 +107,7 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
     L.primitiveFieldRef() = cbrt(mesh.V());
     L.correctBoundaryConditions();
 
-    volScalarField I
+    const volScalarField I
     (
         alpha1
        /max
@@ -116,7 +116,8 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
             pair_.phase1().residualAlpha() + pair_.phase2().residualAlpha()
         )
     );
-    volScalarField magGradI
+
+    const volScalarField magGradI
     (
         max
         (
@@ -125,25 +126,25 @@ Foam::tmp<Foam::volScalarField> Foam::dragModels::segregated::K() const
         )
     );
 
-    volScalarField muI
+    const volScalarField muI
     (
         rho1*nu1*rho2*nu2
        /(rho1*nu1 + rho2*nu2)
     );
-    volScalarField muAlphaI
+
+    const volScalarField muAlphaI
     (
         alpha1*rho1*nu1*alpha2*rho2*nu2
        /(alpha1*rho1*nu1 + alpha2*rho2*nu2)
     );
 
-    volScalarField ReI
+    const volScalarField ReI
     (
-        pair_.rho()
-       *pair_.magUr()
-       /(magGradI*muI)
+        pair_.rho()*pair_.magUr()
+       /(magGradI*alpha1*alpha2*muI)
     );
 
-    volScalarField lambda(m_*ReI + n_*muAlphaI/muI);
+    const volScalarField lambda(m_*ReI + n_*muAlphaI/muI);
 
     return lambda*sqr(magGradI)*muI;
 }
diff --git a/tutorials/multiphase/reactingTwoPhaseEulerFoam/laminar/bubbleColumnIATE/system/setFieldsDict b/tutorials/multiphase/reactingTwoPhaseEulerFoam/laminar/bubbleColumnIATE/system/setFieldsDict
index 7c01263776..58c188396f 100644
--- a/tutorials/multiphase/reactingTwoPhaseEulerFoam/laminar/bubbleColumnIATE/system/setFieldsDict
+++ b/tutorials/multiphase/reactingTwoPhaseEulerFoam/laminar/bubbleColumnIATE/system/setFieldsDict
@@ -17,7 +17,7 @@ FoamFile
 
 defaultFieldValues
 (
-    volScalarFieldValue alpha1 1
+    volScalarFieldValue alpha.air 1
 );
 
 regions
@@ -27,7 +27,7 @@ regions
         box (0 0 -0.1) (0.15 0.701 0.1);
         fieldValues
         (
-            volScalarFieldValue alphaair 0
+            volScalarFieldValue alpha.air 0
         );
     }
 );