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

在过去十年中，极端风事件造成的损失超过了其他所有自然灾害的总和。在飓风、龙卷风、雷暴和其他现象中，几乎美国的每个地区都面临极端风的风险。根据气候模型的预测，这些灾害的发生和严重程度将会升级，这强调了创造抗风建筑的成本效益设计理念的必要性。低层建筑和民用基础设施的结构完整性和长期性能受到这些基础设施所在的近地面大气湍流的严重影响。然而，缺乏对这种流现象的扎实把握，限制了创建风险一致的设计指导的能力。该学院早期职业发展（Career）奖将支持试图通过提高对人口密集环境中的湍流和相关结构风荷载的基本理解来解决这一知识差距的研究。该项目将利用风洞实验、计算机模拟和流体动力学理论发展的结合。该项目的研究成果将有助于改进抗风设计标准，促进国家福利和繁荣。研究活动将辅以教育和推广计划，利用虚拟和增强现实技术的最新进展，加强工程教育的教学和可及性。该奖项将有助于美国国家科学基金会（NSF）在国家风暴影响减少计划（NWIRP）中的作用。该项目的具体目标是双重的：首先是表征湍流和在稳定和非稳定流动条件下导致城市地区极端风事件的基本机制；第二是推导出与风荷载条件的精确表征相关的流量统计的改进解析公式。一系列广泛的风洞试验和高保真的计算流体动力学模拟在理想的城市环境中流动将形成分析的基础。假设雷诺应力预算方程的分析与现代模型简化和相干结构识别技术相结合，将使概念公式的发展成为可能，这些概念公式编码了一阶和高阶流动统计对表面形态和流动强迫条件的依赖性。这些分析模型将被整合到建筑设计规范中，以提高低层结构的弹性，并对大规模社区对不断变化的风灾景观的弹性产生潜在的长期影响。该项目将利用美国国家科学基金会支持的自然灾害工程研究基础设施（NHERI）在佛罗里达大学的边界层风洞，并将在NHERI数据仓库（https://www.DesignSafe-CI.org）.This)中存档和公开项目数据，该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.