Einladung zu einem Vortrag von:
Florian Bachinger
Johannes Kepler Universität Linz
Dienstag, 7. Oktober 2003
13:45 Uhr, T 711
Multigrid Solvers for 3D Nonlinear Multiharmonic
Magnetic Field Computations
The efficient calculation of induction and eddy currents in
electromagnetical problems is of significant interest for many
industrial applications. A fast solver is required for the
endeavor to reduce eddy current losses in electrical machines, for
example, or contrariwise for the optimization of eddy current
welding.
In this talk, we present a rigorous analysis of
the underlying mathematical problem combined with
a strategy for time-discretization which takes advantage of the periodicity of
the solution.
Two main features of eddy current problems complicate the
design of an efficient solver: First, the
relation between magnetic field
strength and induction is in general nonlinear. Secondly,
the magnetic field and the thereby
generated eddy currents hardly penetrate into conducting
materials and thus form a small layer of strong induction
at the boundaries of this material.
This peculiarity leads to difficulties in computations,
because the skin depth has to be considered in the discretization.
We have developped a powerful solver that
handles the problem of the boundary layers
by adaptive refinement and by an increase of the polynomial
degree in the basis functions; the nonlinearity is dealt with
by a Newton iteration.
The capacities of our solver for three-dimensional eddy current problems
are illustrated by
several tests, even including the
challenging real-life problem of eddy current welding.
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