POWRE: Laboratory Experiments of Wind-Raindrop Interactions

9753093 Barros这个项目的目标是通过研究不同坡度、坡度和粗糙度表面上的大气边界层中风雨滴相互作用的基本机制，改进现有的量化降雨影响的经验技术。降雨对裸露地表的影响是建筑物和基础设施恶化的最关键因素之一，也是扩大土壤侵蚀的触发机制。研究方法是根据雨滴的动能和落角来评估降雨影响，这些动能和落角由大气条件(平均风况和动力稳定性参数，如浮力和湍流切变)和降雨的内在特性(强度和雨滴尺寸分布)决定。为此，将在有风和无风的情况下进行降雨影响的声发射测试，同时将使用高分辨率摄影技术来研究雨滴通过大型风洞模拟的湍流边界层的路径和变化。最终，目标是建立风-雨滴相互作用的物理概念框架，以解决广泛的科学和工程问题，例如估计土壤可蚀性指数作为气候的函数，或确定建筑立面的设计标准。POWRE计划提供的支持将用于购置适合同时监测不同地点降雨影响的声学测量装置，并在明尼苏达大学圣安东尼瀑布水利工程实验室进行探索性风洞实验。这些实验对于获得评估拟议研究的可行性和潜在成功所需的数据至关重要，然后才能进行全面调查，以确定大气边界层中雨滴的命运。

9753093 Barros The objective of this project is to improve upon existing empirical techniques to quantify rainfall impact by investigating the basic mechanisms of wind-raindrop interactions in the atmospheric boundary-layer over surfaces of varying slope, aspect and roughness. Rainfall impact on exposed surfaces is one of the most critical agents of deterioration of buildings and infrastructure, and a trigger mechanism of extended soil erosion. The research approach is to assess rainfall impact based on the kinetic energy and angle of impact of raindrops, which are determined by atmospheric conditions (average wind conditions and dynamic stability parameters such as buoyancy and turbulent shear) and the intrinsic properties of rainfall (intensity and raindrop size distribution). For this purpose, acoustic emission testing of rainfall impact will be conducted in the presence and absence of wind, while high-resolution photography will be used to study the pathways and transformations of raindrops moving through turbulent boundary-layers simulated in a large-scale wind tunnel. Ultimately, the goal is to establish a conceptual framework of the physics of wind-raindrop interactions to address a wide range of science and engineering problems, such as to estimate soil erodibility indices as a function of climate, or to define design criteria for building facades. The support provided by the POWRE program will be used for the acquisition of an acoustic measurement unit suitable to monitor the impact of rainfall at various locations simultaneously, and to conduct exploratory wind-tunnel experiments at the Saint Anthony Falls Hydraulic Laboratory, University of Minnesota. These experiments are essential to obtain the data necessary to perform an evaluation of the feasibility and potential success of the proposed research, before a comprehensive investigation to characterize the fate of raindrops in the atmospheric boundary layer can be pursued.