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In this paper we present two different kinds of error estimators for acoustic problems: a residual-based and a dual weighted residual one. The former error estimator is explicit and cheap to compute. The latter is based on a duality argument and it is capable of computing accurate and reliable estimations of quantities of interest, which can be safely used for finite element analysis and model validation. The error estimators presented in this work are designed to work with a $$hp$$-adaptive discontinuous Galerkin methods. [ABSTRACT FROM AUTHOR]

In this paper the discontinuous Galerkin method in time for the coupling of conforming finite element and boundary element methods is established. We derive quasi-optimal a priori error estimates. Numerical examples prove the new scheme to be useful in practice. A posteriori error control and an adaptive algorithm are studied in Part II of this paper. [ABSTRACT FROM AUTHOR]

Fully discrete potential-based finite element methods called $${\mathbf{A}-\phi}$$ methods are used to solve a transient eddy current problem in a three-dimensional convex bounded polyhedron. Using $${\mathbf{A}-\phi}$$ methods, fully discrete coupled and decoupled numerical schemes are developed. The existence and uniqueness of solutions for these schemes together with the energy-norm error estimates are provided. To verify the validity of both schemes, some computer simulations are performed for the model from TEAM Workshop Problem 7. [ABSTRACT FROM AUTHOR]

We explore the prospects of utilizing the decomposition of the function space (H[sup 1, sub 0])[sup n] (where n = 2, 3) into three orthogonal subspaces (as introduced by Velte) for the iterative solution of the Stokes problem. It is shown that Uzawa and Arrow-Hurwitz iterations — after at most two initial — steps can proceed fully in the third, smallest subspace. For both methods, we also compute optimal iteration parameters. Here, for two-dimensional problems, the lower estimate of the inf-sup constant by Horgan and Payne proves useful and provides an inclusion of the spectrum of the Schur complement operator of the Stokes problem. [ABSTRACT FROM AUTHOR]

When simulating electromagnetic phenomena in symmetric cavities, it is often possible to exploit the symmetry in order to reduce the dimension of the problem, thereby reducing the amount of work necessary for its numerical solution. Usually, this reduction leads not only to a much lower number of unknowns in the discretized system, but also changes the behaviour of the coefficients of the differential operator in an unfavourable way, usually leading to the transformed system being not elliptic with respect to norms corresponding to two-dimensional space, thus limiting the use of standard multigrid techniques. In this paper, we introduce a robust multigrid method for Maxwell's equation in two dimensions that is especially suited for coefficients resulting from coordinate transformations, i.e. that are aligned with the coordinate axes. Using a variant of the technique introduced in [5], we can prove robustness of the multigrid method for domains of tensor-product structure and coefficients depending on only one of the coordinates. [ABSTRACT FROM AUTHOR]

The vector potential of a solenoidal vector field, if it exists, is not unique in general. Any procedure that aims to determine such a vector potential typically involves a decision on how to fix it. This is referred to by the term gauging. Gauging is an important issue in computational electromagnetism, whenever discrete vector potentials have to be computed. In this paper a new gauging algorithm for discrete vector potentials is introduced that relies on a hierarchical multilevel decomposition. With minimum computational effort it yields vector potentials whose L²-norm does not severely blow up. Thus the new approach compares favorably to the widely used co-tree gauging. [ABSTRACT FROM AUTHOR]