title: Large-Eddy Simulation of pollutant dispersion around a cubical building: analysis of the turbulent mass transport mechanism by unsteady concentration and velocity statistics.
abstract: Pollutant transport due to the turbulent wind flow around buildings is a complex phenomenon which is challenging to reproduce with Computational Fluid Dynamics (CFD). In the present study we use Large-Eddy Simulation (LES) to investigate the turbulent mass transport mechanism in the case of gas dispersion around an isolated cubical building. Close agreement is found between wind-tunnel measurements and the computed average and standard deviation of concentration in the wake of the building. Since the turbulent mass flux is equal to the covariance of velocity and concentration, we perform a detailed statistical analysis of these variables to gain insight into the dispersion process. In particular, the fact that turbulent mass flux in the streamwise direction is directed from the low to high levels of mean concentration (counter-gradient mechanism) is explained. The large vortical structures developing around the building are shown to play an essential role in turbulent mass transport.
authors.affiliation: Building Physics and Services, Department of the Built Environment, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands. p.gousseau@tue.nl
authors.forename: P
authors.initials: P
authors.lastname: Gousseau
authors.forename: B
authors.initials: B
authors.lastname: Blocken
authors.forename: G J F
authors.initials: GJ
authors.lastname: van Heijst
mesh_terms: D003198:Computer Simulation; D057446:Hydrodynamics; D008956:Models, Chemical; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data
chemical_list: D014874:Water Pollutants, Chemical