Spatial distribution of micellar structure in drag-reducing surfactant solution flow clarified by fluorescence probe method

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06090
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: Osaka City University
• Principal Investigator: Wakimoto Tatsuro 大阪市立大学, 大学院工学研究科, 准教授 (10254385)
• Research Collaborator: Araga Koichi ; Katoh Kenji
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 抵抗低減 / 界面活性剤 / ミセル / 蛍光プローブ / せん断誘起構造

Outline of Final Research Achievements

As widely known, the addition of a specific type of surfactant to liquid in a pipe flow reduces drag remarkably. Previous studies suggested that the drag reduction results from the organized structures of micelles which are aggregation of surfactant molecules. It is interpreted that the organized structure is formed in shear flow and suppress the growth of turbulence. However, the mechanism of the drag reduction is not fully understood since it is very difficult to determine the organized micellar structures formed in the actual moving flow. In this study, we mixed fluorescence probe, which is captured in the micelle, into the liquid, and determined the formation of the organized structures by measuring fluorescence intensity locally. As a result, we clarified that the organized structure formed near pipe wall cause the drag reduction.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果の学術的意義として，まず新しい測定法の提案がある．蛍光プローブ法により，これまで不可能であったミセルの高次組織構造を局所的に検出することが可能となった．また，測定結果から，管壁付近で形成されるミセル組織構造が乱れを抑制していることを明らかにしたことにも大きな意義がある．乱流の乱れはバッファー層と呼ばれる管壁近傍の層で発達することが知られており，ミセル組織構造はこのバッファー層の流れを変えているものと考えられる．活性剤添加による抵抗低減機構が明らかになれば，液体輸送の大幅な省エネ化が可能となるので，この研究成果は社会に大きな貢献をもたらすものでもある．