Surface-mounted bluff bodies immersed in deep turbulent boundary layers

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There have been ever-growing economic and insured losses due to extreme weather over the past two decades.This is related to population growth, population migration to large cities and climate change. The Institute forCatastrophic Loss Reduction (ICLR) is working to develop mitigation strategy with a particular focus onearthquakes, flooding, extreme wind and wildfire. This proposal relates to mitigating the effects of extremewind, particularly, hurricanes and tornadoes. The primary challenge with mitigating wind loads in tornadoes isthat building aerodynamics in tornadoes are largely unknown. The basic approach is to adopt the wind loads for'straight-line' winds (such as hurricanes), and apply a multiplication factor to adopt them for tornadoes. Thechallenge for this is to separate the effects of the swirling vortical structures associated with tornadoes from therest of turbulence, which affects both straight-line winds in the atmospheric boundary layer and tornadoes.The goal of this proposal is to better understand the role of turbulence, in support of ICLR's objective to definewind loads in tornadoes. More specifically, a time-resolved particle image velocimetry will be used to performvelocity measurements in the wake flow generated by three-dimensional surface-mounted bluff bodiesimmersed in deep turbulent boundary layers. The velocity data will be analyzed to develop scientificunderstanding of building aerodynamics, and potentially lead to the development of more reliable predictivemodels that will enable ICLR to develop more effective strategy for mitigating the effects of extreme wind,particularly, hurricanes and tornadoes. The results from this research will also help ICLR to define wind loadsin tornadoes by defining the role of turbulence more precisely.