Research Idea Details

Research Idea Scope

This research project will apply a transport equation to
predict noise distributions in long spaces/enclosures when multiple sources are
present. Potential applications are transportation infrastructures such as
tunnels, subway stations, highway or urban street canyons. This team has
successfully developed and applied a transport equation model [Jing &
Xiang, JASA 127, 2323-2331 (2010)] for a single source with partially diffusive
reflecting surfaces. The team will extend this work to consider multiple
sources at spatially different locations. The computation load for the
transport equation model does not directly depend on the number of sources
modeled. Computational efficiency makes the transport equation model highly
attractive in cases where more than one source is considered, such as multiple
noise sources or linearly distributed noise sources in both sparse and dense
traffic in tunnels, subway stations, urban street canyons, etc..

This project will include:

•             Numerical
implementation of a transport equation for modeling noise propagation in very
long spaces;

•             The
numerical results are compared with those from both the ray-tracing based
method and experimental scale-model results;

•             The
numerical results are compared with those from a few designated sites such as
Holland Tunnel in New York City.

Urgency and Payoff

 Accurately
predicting noise propagation along transportation infrastructures, (such as
highways) is required for noise modeling and the planning of suitable traffic
noise-abatement measures. However, current approaches to modeling noise
propagation rely on conventional methodologies suitable only for open, outdoor
environments. Conversely, traffic noise is profoundly different in enclosed
environments such as underground tunnels, subway stations and dense,
above-ground, canyon-like urban environments dominated by high-rise buildings.

Available geometrical-acoustics approaches require
time-consuming calculations, particularly when considering a large number of
sound sources, (such as densely packed traffic situations where each vehicle
can be considered as a spatially separated noise source). A transport-equation
model is an efficient, cost-effective way to predict noise propagation in long
spaces (such as tunnels, subway stations, traffic noise in urban street
canyons). Spatially distributed noise-sources can be effectively modeled and do
not increase the computational expense from that of the single-source scenario.
For a street canyon scenario with high-rise buildings, the transport equation
can be further simplified to a diffusion equation model. The result is
significantly reduced computational expense coupled with highly accurate
modeling of noise propagation.