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

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.

非均匀表面和不同粗糙度表面上的流动主要是为了阻力目的而进行了广泛的研究。然而，很少有人知道的传输质量动量，热量和相关的阻力发生在地面高架表面粗糙度，称为e-型粗糙度的流动。这对于许多工程应用至关重要，并且在太阳能光化学中特别感兴趣。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考虑正确的风荷载非常重要。本计画的目的是探讨不同的地面粗糙度空间配置如何控制水流中的混合过程与水流结构。最终的问题是，是否有可能通过所提出的布置来操纵流动中的混合和阻力特性。该项目的结果将提高太阳能光伏发电的能量收集效率，从而直接影响太阳能社区，并帮助美国在更短的时间内实现碳中和的目标。该项目还将包括重要的教育活动，包括研究生的夏季交流计划，如何有效地向公众传播科学内容的培训，该项目的目标是发展对地面高架（e型）引起的扰动引起的混合过程的新的理解。表面粗糙度和热展向不均匀性。这项研究的科学成果将包括增强与湍流和热强迫同时存在时复杂表面上发生的混合过程相关的现有知识，以及开发新的缩放关系，其中包括加热和非加热的光动力学启发的地面升高的表面粗糙度元素的影响。该项目的目标将通过协同努力来实现，包括创新的高分辨率大涡模拟（LES）和粒子图像测速在缩放风洞实验。风洞实验将提供瞬时速度场，用于计算涡量预算，从而量化动量交换。LES还将提供瞬时温度场，这也将有助于平衡，说明热效应。这一分析将有助于理解在高粗糙度要素中形成二次环流的因素。除了将在流体力学方面发展新的理解外，拟议的研究还将产生指导未来太阳能光伏发电场设计的关键信息。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。