Characteristics of turbulent puffs and its dependence of generation scheme

2015 Fiscal Year Final Research Report

• Project/Area Number: 25420103
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: Hokkaido University
• Principal Investigator: Tasaka Yuji 北海道大学, 工学(系)研究科(研究院), 准教授 (00419946)
• Co-Investigator(Renkei-kenkyūsha): MURAI Yuichi 北海道大学, 大学院工学研究院, 教授 (80273001)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 乱流遷移 / 流体計測

Outline of Final Research Achievements

We studied process and condition of transition to a turbulent puff that is local turbulence observed in a pipe flow as catastrophic flow transition to turbulence. (1) A fine pipe flow facility with 8 m in the pipe length and 32 mm in the inner diameter of pipe that realizes laminar flow for more than 25,000 of Reynolds number without perturbation was constructed. (2) Novel visualization technique was established to extract vortical structure in a puff effectively. Through experiments, (3) complex edge of turbulence that was found by our previous study was represented in this system and physics embedded in the complex edge was elucidated, and further, (4) influence of adding microbubbles into pipe flows were investigated statistically: turbulent puffs were stabilized by adding bubbles.

Free Research Field

流体力学