EAPSI: A Next-Generation of Wind Fence with Multi-Scale Fractal Structure

了解和控制大气不稳定性，例如风暴引起的突然空气运动，对于研究流体流动的人来说非常感兴趣，因为大气湍流的变化可以用来减少强风。因此，重要的是要了解工程结构，如多孔风栅栏或防风林如何影响各种传入流。本研究将探讨多尺度分形结构诱导的湍流，以更好地控制气流。这项研究将与浦项科技大学（POSTECH）的Sang Joon Lee教授合作进行，他是定量流动可视化、实验流体力学、海崖体空气动力学和生物流体流动方面的专家。由于这项研究涉及新一代风栅栏的大气湍流，因此必须有适当的实验室设备来模拟现实生活条件。主实验室拥有多个风洞，包括大气边界层风洞和各种流量测量系统，为开展这项研究提供了绝佳的位置。从这项研究的见解将有助于工程更有效的防风栅栏，以限制雪/沙沉积在关键基础设施，如道路和桥梁，并减少风对结构本身的整体侧面影响。以前的研究发现，一个定期的单尺度网格栅栏50%的孔隙率和栅栏高度的10%的底部间隙被认为是最佳的平面。由于湍流结构的显着差异已经注意到使用分形风栅栏与此孔隙度标准，本研究的目标是推进知识的诱导流结构和湍流动能输送的一维和二维多尺度分形栅栏在大气边界层条件。具体而言，整个速度场将系统地测量周围的分形栅栏的粒子图像测速（PIV）技术，以揭示的分形栅栏上的湍流的雷诺数范围很广的关键参数的影响。最终，这项研究将有助于设计新一代的分形风栅栏，可以提取足够的动能，从平均风流，以促进雪/沙沉积和防止颗粒再动员过度湍流应力。该奖项由韩国国家研究基金会资助。

Understanding and controlling atmospheric instabilities, such as abrupt air movements resulting from a storm, is of great interest to those who study fluid flow as alterations of atmospheric turbulence can be used to reduce strong winds. It is important, therefore, to understand how engineered structures such as porous wind fences or windbreaks affect various incoming flows. This research will explore multi-scale fractal structure-induced turbulence to better control air currents. The research will be conducted in collaboration with Professor Sang Joon Lee of Pohang University of Science and Technology (POSTECH), an expert in quantitative flow visualization, experimental fluid mechanics, bluff body aerodynamics and bio-fluid flows. Because this study is concerned with atmospheric turbulence for new-generation wind fences, it is imperative to have the appropriate laboratory equipment to simulate real-life conditions. The host laboratory has multiple wind tunnels, including an atmospheric boundary-layer wind tunnel, and various flow measurement systems, providing an excellent location to conduct this research. Insights from this research will contribute to engineering more effective wind fences to limit snow/sand deposition on critical infrastructure such as roads and bridges and to reduce the overall side impact of wind on structures themselves.Previous studies found that a regular mono-scale grid fence of 50% porosity and a bottom gap of 10% of the fence height are considered to be optimal over a flat surface. Since significant differences in turbulent structure have been noted using fractal wind fences with this porosity criteria, the goal of this research is to advance knowledge on the induced flow structure and the turbulence kinetic energy transport of 1D and 2D multi-scale fractal fences in atmospheric boundary-layer conditions. Specifically, whole velocity fields will be systematically measured around the fractal fences by Particle Image Velocimetry (PIV) techniques to uncover effects of key parameters of fractal fences on turbulence for a wide range of Reynolds numbers. Ultimately, this research will assist design of new-generation fractal wind fences which can extract sufficient kinetic energy from the mean wind flow to promote snow/sand deposition and prevent particle remobilization from excessive turbulent stresses. This award is funded in collaboration with the National Research Foundation of Korea.