Validation of simplified urban canopy aerodynamic parameterizations using the CFD simulation of an actual downtown area

  • Nicolas Ramirez

Student thesis: Master's Thesis

Abstract

A steady-state RANS (Reynolds-Averaged Navier-Stokes) Computational Fluid Dynamics (CFD) investigation of a major portion of downtown Abu Dhabi (UAE) was conducted. The results are used to derive the shear stress and characterize the inertial sublayer for 8 sub-domains. The sub-domains are overlapping and overlaid in the streamwise direction. They are characterized by a regularly decreasing frontal area density and a relatively stable plan area density. For each sub-domain, the ‘actual' roughness length and displacement height derived from CFD results are compared to prevalent empirical formulations. We further validate and tune a mixing length model proposed by Coceal and Belcher (2004). Finally, the in-canopy wind speed attenuation is analysed as a function of fetch. It is shown that, while there is some room for improvement in MacDonald's empirical formulations, Coceal and Belcher's mixing model in combination with the resolution method of Di Sabatino, Buccolieri et al. (2008) can provide a robust estimation of the average wind speed in the inertial sublayer. Within the urban canopy, a properly parametrized Cionco (1965) exponential model extending into the roughness sublayer is shown to be quite accurate.
Date of AwardMay 2017
Original languageAmerican English
SupervisorAfshin Afshari (Supervisor)

Keywords

  • Urban Development
  • Abu Dhabi
  • Wind Speed
  • Urban Modelling Urban Canopy
  • Wind Modelling.

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