Abstract
While large eddy simulation has several advantages in microscale air pollutant dispersion modelling, the parametric investigation of geometries is not yet feasible because of its relatively high computational cost. By assuming an analogy between heat and mass transport processes, we utilize a Graphics Processing Unit based software—originally developed for mechanical engineering applications—to model urban dispersion. The software allows for the modification of the geometry as well as the visualization of the transient flow and concentration fields during the simulation, thus supporting the analysis and comparison of different design concepts. By placing passive turbulence generators near the inlet, a numerical wind tunnel was created, capable of producing the characteristic velocity and turbulence intensity profiles of the urban boundary layer. The model results show a satisfactory agreement with wind tunnel experiments examining single street canyons. The effect of low boundary walls placed in the middle of the road and adjacent to the walkways was investigated in a wide parameter range, along with the impact made by the roof slope angle. The presented approach can be beneficially used in the early phase of simulation driven urban design, by screening the concepts to be experimentally tested or simulated with high accuracy models.
Highlights
The increase in the population density of many modern cities is limited by technical issues related to the construction of a healthy and effective living environment
We focused exclusively on cases with the street canyon subjected to a perpendicular wind direction
ANSYS Discovery Live 19.2, which is primarily developed for mechanical engineering
Summary
The increase in the population density of many modern cities is limited by technical issues related to the construction of a healthy and effective living environment. The citizens of such densely populated urban areas benefit from the scientific results of air quality research in the form of improved health conditions. Technological improvements may allow for further increases in population density, long-term benefits might be expected from the urbanization itself (e.g., by creating more job opportunities for individuals, faster development for local enterprises, and a more competitive economy at the national level). Urban air quality displays large fluctuations in both space and time; the mitigation of extremely high local pollution conditions is of particular importance. The street canyon as a minimal model of a city is studied extensively from the perspective of flow structures and transport phenomena. The literature on street canyons was comprehensively reviewed by Vardoulakis et al [3]
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