Hello,
sounds trivial, but how do I create a volScalarField, if I have a Field<double> and a volMesh?

Here mesh.Sf() and U are two volVectorFields from which the operator& calculates the inner product, a scalar field:
Field<double> Phi=mesh.Sf() & U;

But later I need a volScalarField with the values of Phi, and I see no possibility to construct this volScalarField although all geometric information is available.

The problem is that every GeometricField<...> constructor requires an IOobject, and every IOobject constructor requires a filename, so that GeometricFields can never be generated on the fly (unless copied from another GeometricField), but must always be read from a file.

Is this true?

N. Blanc

correction:

1)
"Here mesh.Sf() and U are two volVectorFields..."
should read
"Here mesh.Sf() and U are a surfaceScalarField and a volVectorField..."

2)
"But later I need a volScalarField with the values of Phi, and I see no possibility to construct this volScalarField..."
should read
"But later I need a surfaceScalarField with the values of Phi, and I see no possibility to construct this surfaceScalarField..."

Still the question is:
How can I create a GeometricField from a Field and a Mesh without reading from an IOobject/file?

Best,
N. Blanc

[eugene]

GeometricField.H has all the constructors. There are many. For an example on how to create a field without reading, check this file:

src/finiteVolume/lnInclude/createPhi.H

To reconstruct a face field:

fvc::reconstruct(phi);

or

fvc::average(phi);

Depending on what you want to achieve.

Thank you, Eugene!
My mistake was that I thought an IOobject is always initialized from a file. The example createPhi.H made things clearer.

NB