POWRE: Laboratory Experiments of Wind-Raindrop Interactions

这个项目的目标是改进现有的经验技术，通过研究不同坡度、坡向和粗糙度表面上的大气边界层中风雨相互作用的基本机制，来量化降雨的影响。降雨对暴露地表的影响是导致建筑物和基础设施退化的最重要因素之一，也是引发大面积土壤侵蚀的机制。研究方法是基于雨滴的动能和撞击角度来评估降雨的影响，而雨滴的动能和撞击角度是由大气条件（平均风条件和动力稳定性参数如浮力和湍流切变）和降雨的内在特性（强度和雨滴大小分布）决定的。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研究在大型风洞中模拟的雨滴在湍流边界层中的运动路径和转变。最终，我们的目标是建立一个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，如估计土壤可蚀性指数作为气候的函数，或定义建筑立面的设计标准。POWRE项目提供的支持将用于购置一个声学测量装置，该装置适用于同时监测不同地点降雨的影响，并在明尼苏达大学圣安东尼瀑布水力实验室进行探索性风洞实验。在对大气边界层中雨滴的命运进行全面调查之前，这些实验对于获得评估所提议的研究的可行性和潜在成功所必需的数据是必不可少的。

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.