ENH: potentialFoam: construct Phi with only types() so does not work

for initialising 'complex' bcs. Instead now 'clone' from p. Fixes #153.

applications/solvers/basic/potentialFoam/createFields.H

@@ -93,21 +93,48 @@ if (args.optionFound("writep"))
 
 
 Info<< "Constructing velocity potential field Phi\n" << endl;
-volScalarField Phi
+autoPtr<volScalarField> PhiPtr;
-(
+
-    IOobject
+IOobject io
 (
     "Phi",
     runTime.timeName(),
     mesh,
-        IOobject::READ_IF_PRESENT,
+    IOobject::MUST_READ,
     IOobject::NO_WRITE
-    ),
+);
+
+if (io.typeHeaderOk<volScalarField>())
+{
+    PhiPtr.reset(new volScalarField(io, mesh));
+}
+else
+{
+    // Cannot just use p.boundaryField().types() since does not initialise
+    // complex boundary types. Instead re-clone them from p.
+
+    io.readOpt() = IOobject::NO_READ;
+    PhiPtr.reset
+    (
+        new volScalarField
+        (
+            io,
             mesh,
             dimensionedScalar("Phi", dimLength*dimVelocity, 0),
             p.boundaryField().types()
+        )
     );
 
+    const volScalarField::GeometricBoundaryField& bp = p.boundaryField();
+    volScalarField::GeometricBoundaryField& bPhi = PhiPtr().boundaryField();
+
+    forAll(bp, patchI)
+    {
+        bPhi.set(patchI, bp[patchI].clone(PhiPtr().dimensionedInternalField()));
+    }
+}
+volScalarField& Phi = PhiPtr();
+
 label PhiRefCell = 0;
 scalar PhiRefValue = 0;
 setRefCell