Obtain values only at boundary during a run
 

Dear all,

For my own solver, I need to store only the pressure values at the wall (walls as specified in constant/polyMesh/boundary). This is then used as a source term for dipoles aeroacoustic sources.

I was thinking to store a new volScalarField, with the values for p on the boundary for each time step. The internal field should be zero then.

Is there a simple command to only obtain the boundary values of a volume scalar field, while the internal field should be empty/zero?

Thanks in advance,

Wouter