A Numerical Study of the Updrafts over a Building, with Comparison to Wind - Tunnel Results

There is an opportunity to utilise the updrafts of airflow over buildings for energy harvesting applications; such applications can include enhancing the flight duration of Micro Aerial Vehicles (MAVs) by the exploitation of the vertical velocity components, or locating the over speed regions for the siting of wind generators. In this paper results from a numerical study are compared to a similar wind-tunnel study for the turbulent wind flow conditions around a representative building in an urban environment. The simulation involved a simplified model of a chosen representative building in an urban environment and was initially modelled in two-dimensions, using the standard k-ε turbulence model, which then evolved into a three-dimensional study which utilised the Large Eddy Simulation approach with Smagorinsky-Lilly sub-grid scale modelling. Using meteorological data, the Atmospheric Boundary Layer (ABL) velocity and intensity profiles were modelled at the inlet boundary of the computational domain, to recreate the same test conditions in the wind-tunnel model. It was found that the difference between the numerical model and the wind-tunnel data was less than 20% when comparing the updraft flow field. From the computed results, energy harvesting in the updraft region of buildings seem promising.