STYLE: use ""_deg user-literal for degrees to radians conversion

ENH: add degToRad() multiplier (useful for scalar fields)

- use degToRad() functions throughout instead of scattered local solutions

applications/solvers/multiphase/multiphaseInterFoam/multiphaseMixture/multiphaseMixture.C

@@ -33,12 +33,7 @@ License
 #include "fvcSnGrad.H"
 #include "fvcDiv.H"
 #include "fvcFlux.H"
-
-// * * * * * * * * * * * * * * * Static Member Data  * * * * * * * * * * * * //
-
-const Foam::scalar Foam::multiphaseMixture::convertToRad =
-    Foam::constant::mathematical::pi/180.0;
-
+#include "unitConversion.H"
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
@@ -456,7 +451,7 @@ void Foam::multiphaseMixture::correctContactAngle
 
             bool matched = (tp.key().first() == alpha1.name());
 
-            scalar theta0 = convertToRad*tp().theta0(matched);
+            const scalar theta0 = degToRad(tp().theta0(matched));
             scalarField theta(boundary[patchi].size(), theta0);
 
             scalar uTheta = tp().uTheta();
@@ -464,8 +459,8 @@ void Foam::multiphaseMixture::correctContactAngle
             // Calculate the dynamic contact angle if required
             if (uTheta > SMALL)
             {
-                scalar thetaA = convertToRad*tp().thetaA(matched);
-                scalar thetaR = convertToRad*tp().thetaR(matched);
+                const scalar thetaA = degToRad(tp().thetaA(matched));
+                const scalar thetaR = degToRad(tp().thetaR(matched));
 
                 // Calculated the component of the velocity parallel to the wall
                 vectorField Uwall

applications/solvers/multiphase/multiphaseInterFoam/multiphaseMixture/multiphaseMixture.H

@@ -154,9 +154,6 @@ private:
         //- Stabilisation for normalisation of the interface normal
         const dimensionedScalar deltaN_;
 
-        //- Conversion factor for degrees into radians
-        static const scalar convertToRad;
-
 
     // Private member functions