Fundamental numerical studies of thermal stratification effects in idealized urban areas: Weakly unstable thermal stratification effects on the elongated roll-structures downstream of a high-rise building, and its potential effect on pollutant dispersion in urban areas

Pollution in urban environments is increasingly becoming a major concern for our societies which, together with the increasingly powerful capabilities provided by computational fluid dynamics (CFD), has made pollution dispersion a common topic of research during the last two decades. Several factors are relevant to the dispersion of pollutants...

A rational hybrid RANS-LES model for CFD predictions of microclimate and environmental quality in real urban structures

We report on the application and comparative assessment of two rational turbulence modelling approaches for the computer simulation of air flow and pollutant dispersion in real urban environment: a stand-alone unsteady Reynolds-averaged Navier-Stokes eddy-viscosity model (URANS), and its blend with Large-eddy simulations (LES) in a hybrid...

River-induced anomalies in seasonal variation of traffic-emitted CO distribution over the City of Krasnoyarsk

Seasonal variation of air quality in a city with a large river was investigated by means of numerical simulations of air movement and pollutant dispersion over inversion-capped diurnal cycles using a Reynolds-averaged Navier-Stokes (RANS) approach with algebraic turbulent flux model. The study accounts for the effects of urban heat island ...

Air pollutant sinks on noise barriers: Where do they perform the best?

While laboratory experiments, numerical simulations as well as field tests have underlined the influence of noise barriers in dispersing vehicular emissions and reducing downwind peak concentrations, these pollutants still remain in the atmosphere. Artificial pollutant sinks (for example, particle capturing or toxic gas treating devices)...

Effects of a fence on pollutant dispersion in a boundary layer exposed to a rural-to-urban transition

Simultaneous particle-image velocimetry and laser-induced fluorescence combined with large-eddy simulations are used to investigate the flow and pollutant dispersion behaviour in a rural-to-urban roughness transition. The urban roughness is characterized by an array of cubical obstacles in an aligned arrangement. A plane fence is added one...

Pollution dispersion from highways: Enhancing particulate matter capture using aerodynamics

People living or working close to the highways are at risk to higher exposure levels of different air pollutants, one of which is particulate matter. The Antea group has recently proposed the addition of Electrostatic Precipitators (or ESPs) on the top of sound barriers adjacent to highways, in order to capture the particulate matter and safely...

Pollutant dispersion in boundary layers exposed to rural-to-urban transitions: Varying the spanwise length scale of the roughness

Both large-eddy simulations (LES) and water-tunnel experiments, using simultaneous stereoscopic particle image velocimetry and laser-induced fluorescence, have been used to investigate pollutant dispersion mechanisms in regions where the surface changes from rural to urban roughness. The urban roughness was characterized by an array of...

Stable Stratification Effects on Flow and Pollutant Dispersion in Boundary Layers Entering a Generic Urban Environment

Large-eddy simulations (LES) are used to investigate the effect of stable stratification on rural-to-urban roughness transitions. Smooth-wall turbulent boundary layers are subjected to a generic urban roughness consisting of cubes in an in-line arrangement. Two line sources of pollutant are added to investigate the effect on pollutant dispersion...

The influence of an obstacle on flow and pollutant dispersion in neutral and stable boundary layers

Predicting pollutant dispersion in urban environments requires accurate treatment of obstacle geometry, inflow turbulence and temperature differences. This paper considers both the influence of thermal stratification and the presence of a single obstacle on pollutant dispersion in turbulent boundary layers (TBLs). Turbulent flow over a fence...