interfaceProperties: Name grad(alpha1) "nHat" so that a specific scheme can be selected for it

src/transportModels/interfaceProperties/interfaceProperties.C

@@ -112,7 +112,7 @@ void Foam::interfaceProperties::calculateK()
     const surfaceVectorField& Sf = mesh.Sf();
 
     // Cell gradient of alpha
-    const volVectorField gradAlpha(fvc::grad(alpha1_));
+    const volVectorField gradAlpha(fvc::grad(alpha1_, "nHat"));
 
     // Interpolated face-gradient of alpha
     surfaceVectorField gradAlphaf(fvc::interpolate(gradAlpha));
@@ -123,6 +123,11 @@ void Foam::interfaceProperties::calculateK()
 
     // Face unit interface normal
     surfaceVectorField nHatfv(gradAlphaf/(mag(gradAlphaf) + deltaN_));
+    // surfaceVectorField nHatfv
+    // (
+    //     (gradAlphaf + deltaN_*vector(0, 0, 1)
+    //    *sign(gradAlphaf.component(vector::Z)))/(mag(gradAlphaf) + deltaN_)
+    // );
     correctContactAngle(nHatfv.boundaryField(), gradAlphaf.boundaryField());
 
     // Face unit interface normal flux