An efficient rectilinear Gaussian beam tracing method for sound propagation modelling in a non-turbulent medium

Abstract

Large-distance sound propagation with high-frequency noise sources, multiple obstacles/geometry with varying acoustic impedance is common in real-life applications. To resolve the acoustic governing equations directly is often computationally costly, especially in three-dimensional space. Methods based on geometric acoustics can be more rapid. However, efforts are still being made to improve the efficiency, robustness, and the capability for complex configurations of such methods. In this paper, an efficient implementation of the rectilinear Gaussian beam tracing method is conducted, which combines rectilinear ray tracing with a proposed efficiency-matched dynamic ray tracing algorithm. A continuous medium stratification method is employed to improve the robustness. Also, a ray compression algorithm is proposed to save computation time. Numerical tests show that computation acceleration up to tenfold is achieved, benefiting rapid estimation of large-distance sound propagation. A standard octree data structure is employed in the code, which accelerates ray tracing in the testing cases with complex geometries. The efficiency and capability of the solver are demonstrated by studying several benchmark problems with varying complexity.

Efficient prediction of airborne noise propagation in a non-turbulent urban environment using Gaussian beam tracing method

“…In addition, an adaptive step size strategy is also implemented that makes ray points finer at receiver locations of interest and coarser at other locations. Similar approaches have been introduced and implemented in previous works (Bian et al, 2020;Porter, 2019) to reduce computational cost.…”

“…Nevertheless, in the presence of strong refraction due to wind velocity variations, the GBT prediction deviated up to 10 dB from the experimentally measured results. Recently, several GBT tools (Bian et al, 2020(Bian et al, , 2021Bian et al, 2022;Mo et al, 2017) have been developed and applied to atmospheric acoustic propagation problems. Although these tools are efficient in RPT, they cannot account for atmospheric refraction due to horizontal or vertical variability in the wind velocity in a three-dimensional (3D) environment.…”

“…Applying the GBT method to atmospheric sound propagation poses another intrinsic difficulty that arises when the wavefield is predicated on the terrain surfaces only. Namely, when the beams interact with the terrain boundary, the bottom end of the beam that grazes the terrain boundary passes below the boundary surface, causing spurious truncation error in the wavefield calculation (Bian et al, 2020(Bian et al, , 2021Gabillet et al, 1993). To overcome this intrinsic limitation, Gabillet et al (1993) used large beams and introduced an ad hoc scale factor in the wavefield calculation that accounts for the reflected wavefield.…”

“…Despite the severity of this issue, recent publications did not address it. Those GBT models were validated either against some benchmark cases in ocean acoustics (Bian et al, 2020;Mo et al, 2017) or on elevated surfaces in an outdoor environment where the surface height is a few times larger than the acoustic wavelength (Bian et al, 2020).…”

Aircraft community noise prediction in 3D environment using Gaussian beam tracing

“…Whenever the ray interacts with the terrain boundary, the ray step size is reduced iteratively such that it properly lands on the terrain surfaces; consequently, ray paths are finer in the vicinity of the terrain surfaces and coarser farther away from them. Similar approaches have been introduced and implemented in prior works [18,25] to reduce the computational cost.…”