[makaveli_lcf]

Hi everyone,

I recently ran into what seemed like a trivial issue: dynamically changing the boundary condition of a field, e.g., from 'calculated' to 'fixedValue'. As you know, you can't solve equations in OpenFOAM for fields with 'calculated' type patches, so I needed to explicitly switch them to 'fixedValue'.

Although I expected the solution to be simple and concise, it actually took me quite some time to sort it out, and surprisingly, I couldn't find a clear answer online, even though I remember doing something similar over a decade ago.

I’ve currently tested this approach with OpenFOAM 10, but it should be fairly straightforward to adapt it for use in other versions as well.

So, I’d like to share the working code snippet here in case it saves someone else the trouble:

//  Set boundary type to fixedValue
dictionary dict;
dict.add("value", "uniform (0 0 0)");

forAll(U.boundaryFieldRef(), patchi)
{
    U.boundaryFieldRef().set
    (
        patchi,
        new fixedValueFvPatchVectorField
        (
            mesh.boundary()[patchi],    //  fvPatch reference
            U.ref(),                    //  Internal field reference
            dict
        )
    );
}

Hope this helps someone down the road!

Cheers,