Wave vs. Geometric Based Modeling of Barriers with Atmospheric Effects

Abstract

Wave based solutions of noise barrier geometries accurately model the complex direct, reflected and diffracted sound field interactions. However, typical boundary element and finite element approaches are limited to small geometries and lower frequency ranges because the solutions are very computer intensive and are thus not practical as a design tool. A new class of diffraction based methods, that include phase, are being applied that yield wave-like accuracy with trivial calculation times.

These results, however accurate, typically over-predict the actual performance of noise barriers, because non-homogeneous atmospheric effects such as wind, temperature gradients and turbulence have not been considered. To overcome this limitation, a combined diffraction based barrier model and a heuristic atmospheric model have been developed. Comparisons with the FFT and PE approach show close agreement. Application of this model yield the expected sound barrier performance degradation due to the acoustic medium non-homogeneity.