Print Email Facebook Twitter The influence of an obstacle on flow and pollutant dispersion in neutral and stable boundary layers Title The influence of an obstacle on flow and pollutant dispersion in neutral and stable boundary layers Author Tomas, J.M. Pourquie, M.J.B.M. Jonker, H.J.J. Faculty Mechanical, Maritime and Materials Engineering Department Process and Energy Date 2015-05-13 Abstract 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 with line sources of pollutant in its vicinity is simulated by means of Large-Eddy Simulations. Separate ‘driver’ simulations are done to generate the inflow TBL for several levels of stratification. Using these inflow TBLs the flow development and pollutant dispersion behind the fence, up to 100 fence heights, h, is investigated. It is shown that the decay of velocity and temperature deficit is independent of stability, while the decay of Reynolds stress and concentration excess decreases with increasing stability. For neutral cases the influence of the obstacle is gone after approximately 75h, while for stable cases near the ground the flow is still accelerated compared to the undisturbed case. The fence does cause a local reduction of stratification and thereby increased pollutant dispersion. However, neglecting the effect of buoyancy results in an underestimation of pollutant concentration by a factor 2.5 at 75h downstream of the emission source for the most stable case. Subject stratificationboundary layerobstaclepollutant dispersionturbulencewake To reference this document use: http://resolver.tudelft.nl/uuid:51454527-14fa-447c-9ff7-11c64aa73150 DOI https://doi.org/10.1016/j.atmosenv.2015.05.016 Publisher Elsevier ISSN 1352-2310 Source Atmospheric Environment, 113, 2015 Part of collection Institutional Repository Document type journal article Rights © 2015 The AuthorsThis is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Files PDF Tomas_2015.pdf 1.52 MB Close viewer /islandora/object/uuid:51454527-14fa-447c-9ff7-11c64aa73150/datastream/OBJ/view