Applying the diffusion equation to urban scenarios: computational analysis of the diffusion coefficient

Prediction of sound propagation is playing a key role in the planning and design process of urban areas and during the last decades different techniques have been developed for the computation of the sound fields in cities. Among them, the diffusion equation, based on the propagation of sound energy, is a simple and attractive tool for certain scenarios where the diffuse field is predominant, such as inner city environments. The diffusion equation is a well-known and efficient method to compute sound fields in rooms with a low amount of absorption. However, this method, which includes the diffusion coefficient describing the diffusivity of the energy propagation, requires further understanding for urban environments. In this work, the diffusion coefficient has been evaluated using wave-based numerical techniques for simplified two-dimensional urban scenarios. The parameter is computed spatially from the acoustic intensity and sound energy density fields in every direction for different geometries. This paper investigates the directional components of the diffusion coefficient.