ENH: Added helper include file to create radiation model for incompressible cases

src/thermophysicalModels/radiationModels/include/createIncompressibleRadiationModel.H

@@ -0,0 +1,32 @@
+    autoPtr<radiation::radiationModel> radiation
+    (
+        radiation::radiationModel::New(T)
+    );
+
+    dimensionedScalar rhoCpRef
+    (
+        "rhoCpRef",
+        dimDensity*dimEnergy/dimMass/dimTemperature,
+        1.0
+    );
+
+    if (radiation->radiation())
+    {
+        IOdictionary transportProperties
+        (
+            IOobject
+            (
+                "transportProperties",
+                runTime.constant(),
+                runTime,
+                IOobject::MUST_READ,
+                IOobject::NO_WRITE,
+                false  // do not register!
+            )
+        );
+
+        dimensionedScalar rhoRef(transportProperties.lookup("rhoRef"));
+        dimensionedScalar CpRef(transportProperties.lookup("CpRef"));
+
+        rhoCpRef = rhoRef*CpRef;
+    }