Generation of quasi homogeneous isotropic turbulence with no mean flow using Megahertz ultrasonic tranceducers

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K13867
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Fluid engineering
• Research Institution: Nagoya University
• Principal Investigator: Nagata Koji 名古屋大学, 工学研究科, 教授 (50274501)
• Co-Investigator(Renkei-kenkyūsha): IWANO Koji 名古屋大学, 大学院工学研究科, 助教 (20750285) ; ITO Yasumasa 名古屋大学, 大学院工学研究科, 准教授 (40346078) ; SAKAI Yasuhiko 名古屋大学, 大学院工学研究科, 教授 (20162274)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 流体工学 / 乱流 / 超音波 / 格子乱流

Outline of Final Research Achievements

A grid tank in which turbulence is generated by a grid and steady flow (i.e., acoustic streaming) when Megahertz (0.95 MHz) ultrasound is irradiated into a quiescent water is newly designed and manufactured. The characteristics of created turbulent flows are measured by using particle image velocimetry (PIV). The mesh length of the grid is M=20 mm and the thickness of the square bar is 4 mm, so that its solidity is 36%. In order to further elucidate the characteristics of the turbulent field, a numerical code for direct numerical simulation of temporally developing grid turbulence is newly developed based on the finite difference method. The calculations are conducted on a supercomputer for the mesh Reynolds numbers of 10,000 and 20,000. The characteristics of the turbulent flow are investigated by above-mentioned experiments and calculations.

Free Research Field

流体工学