Print Email Facebook Twitter Effects of a fence on pollutant dispersion in a boundary layer exposed to a rural-to-urban transition Title Effects of a fence on pollutant dispersion in a boundary layer exposed to a rural-to-urban transition Author Eisma, H.E. (TU Delft Fluid Mechanics) Tomas, J.M. (TU Delft Fluid Mechanics) Pourquie, M.J.B.M. (TU Delft Fluid Mechanics) Elsinga, G.E. (TU Delft Fluid Mechanics) Jonker, H.J.J. (TU Delft Atmospheric Physics) Westerweel, J. (TU Delft Fluid Mechanics) Date 2018 Abstract 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 obstacle height h upstream of the urban roughness elements, with three different fence heights considered. A smooth-wall turbulent boundary layer with a depth of 10h is used as the approaching flow, and a passive tracer is released from a uniform line source 1h upstream of the fence. A shear layer is formed at the top of the fence, which increases in strength for the higher fence cases, resulting in a deeper internal boundary layer (IBL). It is found that the mean flow for the rural-to-urban transition can be described by means of a mixing-length model provided that the transitional effects are accounted for. The mixing-length formulation for sparse urban canopies, as found in the literature, is extended to take into account the blockage effect in dense canopies. Additionally, the average mean concentration field is found to scale with the IBL depth and the bulk velocity in the IBL. Subject Large-eddy simulationLaser-induced fluorescenceMixing-length modelPollutant dispersionStereoscopic particle-image velocimetry To reference this document use: http://resolver.tudelft.nl/uuid:c5ee953e-21c0-4dbd-b3d2-e51fd782e708 DOI https://doi.org/10.1007/s10546-018-0367-1 ISSN 0006-8314 Source Boundary-Layer Meteorology: an international journal of physical and biological processes in the atmospheric boundary layer, 169 (2), 185-208 Part of collection Institutional Repository Document type journal article Rights © 2018 H.E. Eisma, J.M. Tomas, M.J.B.M. Pourquie, G.E. Elsinga, H.J.J. Jonker, J. Westerweel Files PDF Eisma2018_Article_Effects ... ntDisp.pdf 2.59 MB Close viewer /islandora/object/uuid:c5ee953e-21c0-4dbd-b3d2-e51fd782e708/datastream/OBJ/view