Unsteady Urban Airflows and Their Impact on Small Unmanned Air System Operations

Existing Unmanned Air System (UAS) platforms currently do not lend themselves well to autonomous operation within complex, highly-variable aerodynamic environments. As such, there is a strong need for accurate, high-fidelity urban air flow models to help reduce risk of failure of urban UAS surveillance and engagement missions. Although urban aerodynamics are exceptionally complicated because of complex interactions between geometry, physical conditions, and varying meteorology, research-caliber Computational Fluid Dynamics (CFD) models exist that capture these interactions effectively. Using sufficient resolution, these Large Eddy Simulation models provide a viable means to characterize urban environments when wind tunnel testing and field trials are too expensive and/or impossible. We have successfully integrated these extant CFD models and their real-time effects on embedded UAS within a synthetic modeling environment. By further incorporating urban terrain, UAS aerodynamic data, and a UAS vehicle dynamics model, a real-time physicsbased simulation tool has been created for the study of vehicle-environment interactions. This paper will discuss how this tool could revolutionize our understanding of these interactions in urban environments, giving unprecedented capability and flexibility to UAS designers, acquisition agents, mission planners, and operators.