Building Resolving Urban Microscale Weather for UAS/UAM Applications

Over 80% of the United States (US) population currently resides in urban areas (US Census Bureau, 2018) and the World Bank and United Nations both anticipate continued increases in the world’s urban population throughout the next century. Concerns about transportation congestion associated with these current and projected population increases as well as advancements in unmanned aircraft and communications technologies have led to a wave of interest and investment in Unmanned Aircraft Systems (UAS) and Urban Air Mobility (UAM) solutions. While arange of modeling capabilities exist today that are capable of resolving the urban wind conditions most lack the required spatial/temporal fidelity necessary for this application. For the models that can meet the necessary spatial/temporal fidelity for urban UAS/UAM applications, the computational requirements have limited their use to only idealized studies.

In this presentation we will describe a Large Eddy Simulation (LES) system called the Joint Outdoor Urban-indoor LES (JOULES) that has both the spatial/temporal fidelity and simulation speeds necessary to address the UAS/UAM microscale urban weather needs described above. A key enabling technology within JOULES is a LES that has been implemented on a graphics processing unit (GPU) computing platform. The LES within JOULES traces its origins back several decades to the Dutch Atmospheric LES (DALES) which is one of the most extensively tested LES codes for use in planetary boundary layer (PBL) applications (Heus et al. 2010). This model has been extensively evaluated and Schalkwijk et al. 2012, 2015, and 2016 and Bieringer et al. (2017, 2019) have demonstrated that this GPU-LES model can accurately simulate atmospheric conditions and corresponding dispersion in open-terrain environments across a range of static stability (e.g. daytime through nighttime) conditions. JOULES also utilizes an immersed boundary method (IBM) implementation that enables the simulation of high Reynolds number flows in urban environments at spatial resolutions down to 1-meter. In this presentation we will provide a description of this modeling system, show a variety of results from validation studies illustrating the model’s performance across a range of environmental conditions in both open terrain and urban environments, show illustrations of urban building-resolving simulations that cover the urban core of downtown Chicago, and discuss the potential implications of this technologies use for urban microscale aviation weather applications.