In this paper, we focus on an a posteriori residual-based error estimator for the T/Ω
magnetodynamic harmonic formulation of the Maxwell system. Similarly to the A/ φ formulation
[7], the weak continuous and discrete formulations are established, and the well-posedness of
both of them is addressed. Some useful analytical tools are derived. Among them, an ad-hoc
Helmholtz decomposition for the T/
Ω case is derived, which allows to pertinently split the error.
Consequently, an a posteriori error estimator is obtained, which is proven to be reliable and locally
efficient. Finally, numerical tests confirm the theoretical results.