A 2.5D acoustic finite element method applied to railway acoustics

Railway acoustic problems commonly have a constant cross-section and uniform properties in the longitudinal direction. To solve such 3D with reduced effort, wavenumber domain finite element (2.5D FE) method is introduced which of meshed third dimension represented by transform. The thereby decomposed into combination wavenumbers x direction y-z plane. extended to exterior noise including perfectly matched layer (PML) bespoke absorption prevent reflection sound waves at boundary domain. as presented can be used 2D solutions from commercial software. verify application 2.5D FE for interior problems, attenuation tunnel predicted compared existing measurements. implementation an example given distribution on side surface train due compact source below it. comparison obtained models measurements shows good agreement both validation cases. then investigate effect walls external comparing results case open field. A highly reverberant field found tunnels, increases pressure level side-surface above 250 Hz about 10 dB ballasted track further 6 slab track.