driftFluxFoam: use buoyancy corrected k-epsilon in all turorials

tutorials/multiphase/driftFluxFoam/ras/mixerVessel2D/constant/turbulenceProperties

@@ -19,10 +19,15 @@ simulationType  RAS;
 
 RAS
 {
-    RASModel kEpsilon;
+    RASModel buoyantKEpsilon;
 
     turbulence      on;
     printCoeffs     on;
+
+    buoyantKEpsilonCoeffs
+    {
+        Cg      0.85;
+    }
 }
 
 // ************************************************************************* //

tutorials/multiphase/driftFluxFoam/ras/tank3D/constant/turbulenceProperties

@@ -19,10 +19,15 @@ simulationType  RAS;
 
 RAS
 {
-    RASModel kEpsilon;
+    RASModel buoyantKEpsilon;
 
     turbulence      on;
     printCoeffs     on;
+
+    buoyantKEpsilonCoeffs
+    {
+        Cg      0.85;
+    }
 }
 
 // ************************************************************************* //