Experimental and numerical study on generation of ideal oscillating grid turbulence and turbulence diffusion process

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02064
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Morinishi Yohei 名古屋工業大学, 工学(系)研究科(研究院), 教授 (40222351)
• Co-Investigator(Kenkyū-buntansha): 玉野 真司 名古屋工業大学, 工学(系)研究科(研究院), 教授 (40345947) ; 山田 格 名古屋工業大学, 工学(系)研究科(研究院), 助教 (40772067)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 乱流 / 振動格子乱流 / 実験計測 / DNS

Outline of Final Research Achievements

The turbulence generated by grid oscillation was investigated experimentally and numerically. Some devices were added to the experimental apparatus for reducing the inherent secondary flow. The fast algorithm for the DNS of the oscillating grid turbulence was composed based on the influence matrix and domain decomposition methods.
The effect of the secondary flow on the turbulence was reduced by the devices in the experiment. It was also revealed that a slight system rotation drastically reduced the secondary flow. The decay behavior of the experimental turbulence intensity was well corresponding to that of the DNS, where the DNS flow field was ideal in the sense that there is no secondary flow. The turbulence structure of the oscillating grid turbulence was further investigated by using the experimental and numerical flow fields.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

近年の地球温暖化やそれに伴って生じる自然災害、例えば集中豪雨、台風、および竜巻等の発生や進路予測について、その信頼性は現状では十分とは言えない。これら乱流に深く関わる現象に対しては、個々の現象の探求はもちろん必要であるが、乱流に共通な本質的要素を理解するため、特に基礎研究が重要である。本研究で取り上げた振動格子乱流は乱流の本質である非線形干渉から生じる乱流拡散を調べるのに適した乱流場である。従って、本研究で示した実験装置の工夫や新たな計算アルゴリズムの構築は、乱流研究の今後の発展に貢献するものである。