Investigating voltage excitation of the Darwin model via the prescription of terminal scalar potentials

Developing simulation models for electromagnetic field problems often deals with approximations of the full set of Maxwell's equations, to obtain performant methods. This is also the case for the so-called Darwin model, which has the capability of including resistive, inductive, and capacitive effects without the need of solving full-wave Maxwell's equations. However, an issue is the difficulty of prescribing realistic excitations of the model, e.g., via a terminal voltage. In this article, the straightforward prescription of the scalar potential on electric ports is investigated via Poynting's theorem, with the outcome that it can be considered as physical voltage excitation up to frequencies, where the validity of the Darwin model itself is lost.