Abstract.We consider the time-harmonic eddy current problem in its electric formulation where the conductor is a polyhedral domain. By proving the convergence in energy, we justify in what sense this problem is the limit of a family of Maxwell transmission problems: Rather than a low frequency limit, this limit has to be understood in the sense of Bossavit [11]. We describe the singularities of the solutions. They are related to edge and corner singularities of certain problems for the scalar Laplace operator, namely the interior Neumann problem, the exterior Dirichlet problem, and possibly, an interface problem. These singularities are the limit of the singularities of the related family of Maxwell problems.
Mathematics Subject Classification. 35B65, 35R05, 35Q60.Received: May 20, 2003.
Maxwell equations and the eddy current limitLet us consider the model case of an homogeneous conducting body Ω C which we assume to be a threedimensional bounded polyhedral domain with a Lipschitz boundary B. The conductivity σ = σ C is constant and positive inside Ω C , while σ vanishes outside Ω C , i.e., σ ≡ 0 in the "air" (or "empty") region Ω E = R 3 \ Ω C . For the sake of simplicity we further assume that the boundary B of Ω C is connected ( * ) . The electric permittivity ε is equal to a positive constant ε C inside Ω C and has another value ε E in the exterior medium. Similarly, the magnetic permeability µ is equal to µ C > 0 in Ω C and to µ E > 0 in Ω E . The treatment of piecewise constant σ C , ε C , µ C and µ E can be made in a similar manner.
Maxwell and eddy current problemsLet ω > 0 be a fixed frequency. The time harmonic Maxwell equations are