Non-Intrusive Methods for the Cosimulation of Coupled Problems

Many industrial applications require transient simulations of coupled problems. The coupling can involve multiples physical disciplines, multiple scales in space and time and different requirements on simulation accuracy and efficiency. In many cases, the coupling necessitates a decoupling of the time-stepping procedure, either because different software packages each have their own time stepper, or in order to improve the overall simulation efficiency, e.g. if multirate behaviour is present. In this chapter, two advanced cosimulation approaches are presented: dynamic iteration (waveform relaxation) and a fractional splitting equipped with error correction. These schemes provide an efficient numerical set-up despite large differences in time scales or the high nonlinearity of the coupling terms. The methods are illustrated for a field-circuit coupled magnetoquasistatic finite-element model of a power transformer and for an electrothermal finite-integration model of an electronic package.