Scale-resolving simulation to predict the updraught regions over buildings for MAV orographic lift soaring

Birds have been observed to soar over ridges, mountains and cliffs to extend their flight duration with minimal energy expenditure. There is an opportunity to replicate this behavior to enhance the flight duration of Micro Aerial Vehicles (MAVs) which operate in urban environments by exploiting the vertical flow component (orographic lift) of flow over buildings. This paper therefore studies the flow field in a representative urban environments to enhance the operational capability of MAV platforms by increasing range and endurance. The feasibility and benefits of employing Computational Fluid Dynamics (CFD) are investigated, to simulate the turbulent wind flow conditions around a building configuration. A three-dimensional, scale-resolving simulation, utilizing a derivative of the Detached Eddy Simulation approach was considered. The atmospheric boundary layer velocity and turbulent intensity profiles were calibrated at the inlet boundary of the computational domain, to replicate nominal operating conditions. Recent validation of the Improved Delayed Detached Eddy Simulation (IDDES) approach has shown excellent agreement for a number of relevant flows. This provided the motivation for the study of a full-scale multi-building configuration, and suggests that the use of high-fidelity turbulence modeling is able to predict updraught regions of buildings in an urban environment.