fixedMeanFvPatchField: Evaluate on construction from dictionary

to ensure the values on the patch are consistent with the boundary condition
specification and to avoid the need to specify a potentially inconsistent
"value" entry.

src/finiteVolume/fields/fvPatchFields/derived/fixedMean/fixedMeanFvPatchField.C

@@ -36,7 +36,7 @@ Foam::fixedMeanFvPatchField<Type>::fixedMeanFvPatchField
     const dictionary& dict
 )
 :
-    fixedValueFvPatchField<Type>(p, iF, dict),
+    fixedValueFvPatchField<Type>(p, iF),
     meanValue_
     (
         Function1<Type>::New
@@ -47,7 +47,9 @@ Foam::fixedMeanFvPatchField<Type>::fixedMeanFvPatchField
             dict
         )
     )
-{}
+{
+    this->evaluate();
+}
 
 
 template<class Type>

tutorials/fluid/helmholtzResonance/0/p

@@ -29,7 +29,6 @@ boundaryField
     {
         type            fixedMean;
         meanValue       constant 1 [bar];
-        value           $internalField;
     }
 
     symmetry