How to Parametrize Urban-Canopy Drag to Reproduce Wind-Direction Effects Within the Canopy
- 496 Downloads
The mean wind direction within an urban canopy changes with height when the incoming flow is not orthogonal to obstacle faces. This wind-turning effect is induced by complex processes and its modelling in urban-canopy (UC) parametrizations is difficult. Here we focus on the analysis of the spatially-averaged flow properties over an aligned array of cubes and their variation with incoming wind direction. For this purpose, Reynolds-averaged Navier–Stokes simulations previously compared, for a reduced number of incident wind directions, against direct numerical simulation results are used. The drag formulation of a UC parametrization is modified and different drag coefficients are tested in order to reproduce the wind-turning effect within the canopy for oblique wind directions. The simulations carried out for a UC parametrization in one-dimensional mode indicate that a height-dependent drag coefficient is needed to capture this effect.
KeywordsDirect numerical simulations (DNS) Drag coefficients Reynolds-averaged Navier–Stokes (RANS) Urban-canopy parametrization Wind direction
This study has been partially supported by the project Modelización de la Influencia de la Vegetación Urbana en la Calidad del Aire y Confort Climático (CGL2011-26173) funded by Spanish Ministry of Economy and Competitiveness and by the Project Supercomputation and E-Science (SyeC) from the Spanish CONSOLIDER Programme.
- Bezpalcova K (2006) Physical modelling of flow and diffusion in urban canopy. PhD thesis, Charles University, PragueGoogle Scholar
- Biltoft CA (2001) Customer report for Mock Urban Setting Test (MUST). DPG document WDTC-TP-01-028, West Desert Test Center, S. Army Dugway Porving Ground, Dugway, Utah, p 58Google Scholar
- Brown M, Williams M (1998) An urban canopy parameterization for mesoscale meteorological models. In: AMS 2nd urban environment symposium, Albuquerque, NM, pp 144–147Google Scholar
- Carissimo B, Macdonald RW (2004) A porosity/drag approach for the modeling of flow and dispersion in the urban canopy. In: Borrego C, Schayes G (eds) Air pollution modelling and its applications XV. Springer, New YorkGoogle Scholar
- CD-adapco (2012) User Guide STAR-CCM+ Version 7.04.011. Cd-adapco, p 11448Google Scholar
- Dejoan A, Santiago JL, Martilli A, Martin F, Pinelli A (2010) Comparison between large-eddy simulation and Reynolds-averaged Navier–Stokes computations for the MUST field experiment. Part II: effects of incident wind angle deviation on the mean flow and plume dispersion. Boundary-Layer Meteorol 135:133–150CrossRefGoogle Scholar