Physical modeling of turbulence reduction by surfactant additives

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K14893
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Hokkaido University (2020); Tokyo University of Science (2019)
• Principal Investigator: HORIMOTO Yasufumi 北海道大学, 工学研究院, 特任助教 (60822525)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 抵抗低減 / 乱流 / Taylor-Couette流 / 粒子画像流速測定 / PIV / 蛍光プローブ法 / 界面活性剤水溶液

Outline of Final Research Achievements

To experimentally investigate the drag reduction by surfactant additives into high-Reynolds number turbulence of water, we produce a very large apparatus of Taylor-Couette flow. By the addition of surfactant to the turbulence of water with concentrations of the order of O(10) ppm, angular momentum transfer is drastically suppressed, which achieves the reduction of drag by 50 %. By velocity measurements, we reveal that in such a drag-reduced state, the mean velocity distribution between the rotating inner and outer cylinders is not monotonical. In addition, we conduct fluorescence probe method to relate the drag-reduced state to the existence of micellar structures. We confirm that a correlation between the above measurements when the drag reduction occurs.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

持続可能な社会実現のためには、工業の場面での省エネルギー化が喫緊の課題である。本研究では、パイプライン中の乱流によるエネルギーの摩擦損失を低減する技術としられる、界面活性剤添加による抵抗低減現象のメカニズム解明に取り組んだ。測定原理の異なる計測手法を組み合わせて実験を行うことで、抵抗低減の発現と特異な平均流速分布、水溶液中の界面活性剤ミセル構造の存在を関連付けることができた。これは、抵抗低減の予測には欠かすことのできない、現象の数理モデルの構築に寄与する結果である。