CAREER: Characterization of Turbulence in Urban Environments for Wind Hazard Mitigation

In the past decade, losses from extreme wind events have exceeded those from all other natural disasters combined. Among hurricanes, tornadoes, thunderstorm downbursts, and other phenomena, virtually every region of the U.S. is at risk of extreme winds. Predictions from climate models anticipate an escalation in the occurrence and severity of these hazards, underscoring the need for cost-effective design concepts to create wind-resistant buildings. The structural integrity and long-term performance of low-rise buildings and civil infrastructure are heavily influenced by atmospheric turbulence near ground level where this infrastructure exists. Yet, a solid grasp of this flow phenomenon is lacking, limiting the ability to create risk-consistent design guidance. This Faculty Early Career Development (CAREER) award will support research that attempts to address this knowledge gap by advancing the fundamental understanding of turbulence in densely populated environments and the associated wind loads on structures. The project will utilize a combination of wind tunnel experiments, computer simulations, and theoretical developments in fluid dynamics. Findings from this project will enable improvements in wind-resistant design standards, bolstering national welfare and prosperity. Research activities will be complemented by an educational and outreach program leveraging recent advances in virtual and augmented reality technology to enhance teaching and accessibility to engineering education. This award will contribute to the U.S. National Science Foundation (NSF) role in the National Windstorm Impact Reduction Program (NWIRP).The specific objective of this project is twofold: the first is to characterize turbulence and fundamental mechanisms responsible for extreme wind events in urban areas under stationary and non-stationary flow conditions; the second is to derive improved analytical formulations for flow statistics that are relevant to the precise characterization of wind-loading conditions. An extensive series of wind tunnel tests and high-fidelity computational fluid dynamics simulations of flow over idealized urban environments will form the basis for the analysis. The hypothesis is that analysis of Reynolds stress budget equations combined with modern model reduction and coherent-structures identification techniques will enable the development of conceptual formulations encoding the dependency of first and higher order flow statistics onto surface morphology and flow forcing conditions. The analytical models will be derived for integration within building design codes to improve the resilience of low-rise structures, with potential long-lasting impacts on large-scale community resilience to the changing landscape of wind hazards. The project will utilize the NSF-supported Natural Hazards Engineering Research infrastructure (NHERI) Boundary Layer Wind Tunnel at the University of Florida and will archive and make publicly available the project data in the NHERI Data Depot (https://www.DesignSafe-CI.org).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.