Homogenisation of perforated plates

The effects of small apertures perforating a thin plate and the appropriate homogenised boundary condition one should apply when such a plate is placed in flow is considered. Specific attention is placed on a boundary condition applicable to acoustic scattering by an incident plane wave. The perforated plate is both modelled explicitly via Mathieu function collocation and the impact of appropriate homogenisation on the far-field scattered noise is investigated via use of the Wiener-Hopf technique. Both uniformly sized apertures and non-uniformly sized apertures are considered.