Zooming into the near field: Shear-horizontal polarized acoustic waves

The boundary element method is a versatile and powerful numerical technique which has been successfully applied to numerous problems in device modelling at various scales and frequency ranges. The underlying system of surface integrals involve (dyadic) Green´s functions and their spatial derivatives which are singular with varying degree of singularity. While the singularities are as a rule integrable, sophisticated regularization techniques are required to assure reliable numerical results in terms of accuracy and robustness. In particular in the near-field region, where the observation point and the source point become critically close or even coincide, the analytical and numerical calculations may turn out to be prohibitively complicated. In this paper, utilizing a model problem, a novel technique for treating near-field problems has been presented. An easy-to-use, and conceptually clear recipe has been developed which is applicable to a myriad of modelling and simulation problems in computational engineering. The presented method enables zooming into the near-field with arbitrary degree of precision.