Three dimensional analysis of the vertical jet in a density stratified fluid

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K17972
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Fluid engineering
• Research Institution: Kyoto University
• Principal Investigator: Okino Shinya 京都大学, 工学研究科, 助教 (30711808)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 密度成層 / 高シュミット数 / ジェット / 乱流遷移 / 内部重力波

Outline of Final Research Achievements

The flow around a sphere descending at a constant speed in a salt-stratified fluid is investigated by the shadowgraph method and the PIV method. The thickness of the axisymmetric jet behind the sphere is estimated by the square root of the Froude number divided by the Reynolds number in accordance with the prediction by a dimensional analysis. We have found that the jet becomes turbulent in a very strongly stratified fluid (at the Froude number less than 0.1) even though the Reynolds number is as small as 50. Our direct numerical simulations have reproduced the non-axisymmetric/axisymmetric vortex shedding at the Froude number larger than 10, which was observed by the previous experiments.

Free Research Field

流体力学