Collaborative Research: Transport and mixing processes in turbulent boundary layers over ground-elevated surface roughness

合作研究：地表粗糙度上湍流边界层的传输和混合过程

• 批准号: 2235750
• 负责人: Marc Calaf
• 金额: $ 26.84万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2235750&HistoricalAwards=false
• 关键词: Collaborative; Research; Transport; mixing; processes; Collaborative; Research; Transport; mixing; processes

Flows over heterogeneous surfaces and over different types of roughness have been extensively studied primarily for drag purposes. However, very little is known about the transport of mass momentum, heat and associated drag occurring in flows over ground-elevated surface roughness, named e-type roughness. This is critical for numerous engineering applications and of particular interest in solar photovoltaics. This is because convective cooling plays a critical role in controlling solar photovoltaics efficiency, and accounting for the right wind loads is important when designing new installations. The goal of this project is to investigate how different spatial arrangements of the ground-elevated surface roughness control mixing processes and flow structures in the flow. The ultimate question is whether it is possible to manipulate the mixing and drag characteristics in the flow through the proposed arrangements. Results of this project will enhance solar photovoltaics energy harvesting efficiency, thereby directly impacting the solar energy community and helping transition the U.S. into meeting the goal of becoming carbon neutral in a shorter period of time. The project will also encompass significant educational activities, including summer exchange programs for the graduate students, training on how to effectively communicate science content to the general public, and the development of training videos for the solar energy community.The goal of this project is to develop new understanding about mixing processes that result from the perturbations induced by ground-elevated (e-type) surface roughness and thermal spanwise heterogeneities. The scientific outcomes of this research will include enhancement of the current knowledge related to mixing processes over complex surfaces taking place when both turbulence and thermal forcings are simultaneously present and development of new scaling relations that include the effect of heated and non-heated photovoltaics-inspired ground-elevated surface roughness elements. The objectives of this project will be fulfilled through a synergistic effort including innovative high-resolution large-eddy simulations (LES) and particle image velocimetry in scaled wind tunnel experiments. The wind tunnel experiments will provide instantaneous velocity fields which will be used to compute the budget of vorticity, thus quantifying the momentum exchanges. The LES will also provide the instantaneous temperature fields which will also contribute to the balance, accounting for thermal effects. This analysis will facilitate understanding the factors contributing to the formation of secondary circulations in elevated roughness elements. In addition to the new understanding that will be developed in fluid mechanics, the proposed research will also yield critical information to guide the design of future solar photovoltaic farms.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.

在异质表面和不同类型的粗糙度上的流动主要是出于阻力目的进行了广泛的研究。但是，关于质量动量，热量和相关阻力的运输知之甚少，在地面的表面粗糙度（称为e型粗糙度）上发生。这对于众多工程应用至关重要，对太阳能光伏特别感兴趣。这是因为对流冷却在控制太阳能光伏效率方面起着至关重要的作用，并且在设计新装置时，对正确的风负荷进行了计算。该项目的目的是研究如何在流动中的地面表面粗糙度控制过程和流量结构的不同空间排列。最终的问题是，是否有可能操纵通过提出的布置的流动中的混合和阻力特征。该项目的结果将提高太阳能光伏能源收集效率，从而直接影响太阳能社区，并帮助美国过渡到较短时期内成为碳中性的目标。该项目还将涵盖重大的教育活动，包括针对研究生的夏季交流计划，有关如何有效地将科学内容传达给公众的培训，以及为太阳能能源社区开发培训视频。该项目的目的是建立对由地面（e-e-type）表面粗糙度和热量跨度的扰动引起的对混合过程的新理解。这项研究的科学结果将包括增强与当前在复杂表面上的混合过程相关的知识，同时存在湍流和热强迫，以及新的缩放关系的发展，包括加热和非热的光伏和非热的光伏启用的效果。该项目的目标将通过协同的努力来实现，包括创新的高分辨率大涡模拟（LES）和粒子图像实验中的粒子图像实验。风洞实验将提供瞬时速度场，该速度场将用于计算涡度预算，从而量化动量交换。 LES还将提供瞬时温度场，这也将导致平衡，并考虑热效应。该分析将有助于理解导致较高粗糙度元素中次级循环形成的因素。除了在流体力学中发展的新理解外，拟议的研究还将产生关键信息，以指导未来的太阳能光伏农场的设计。该奖项反映了NSF的法定任务，并被认为值得通过基金会的知识分子优点和更广泛的影响审查标准通过评估来获得支持。