Prediction of Drag Reduction Effect of Hydrogel Painting Having Shear Stress Responsibility by Using Mesoscale Model

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06963
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Naval and maritime engineering
• Research Institution: Yokohama National University
• Principal Investigator: Takagi Youhei 横浜国立大学, 大学院工学研究院, 准教授 (40435772)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 機能性船底塗料 / ハイドロゲル / 乱流 / 抵抗低減 / 水槽試験 / 直接数値計算

Outline of Final Research Achievements

We have carried out the resistance test with a water tank and a simulation in order to investigate the frictional drag reduction of hydrogel paint that is one of the functional paints of ship hull used in commercial large ship. At the water tank experiment, the frictional drag on a flat plate coated with hydrogel paint was measured in a uniform flow. From the experimental result, it was found that turbulent eddy structures were different in the laminar-turbulence transition regime and fully-developed turbulence state, and the drag reduction effect became prominent in the transition regime. In addition, the roughness of painting film was numerically changed from homogenous pattern to anisotropic one and the flow simulation was conducted. From the numerical result, it was shown that the drag reduction effect was obtained due to the shear stress response of hydrogel paint if rough film was used.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

機能性船底塗料の一つであるハイドロゲル塗料の摩擦抵抗低減効果をメソスケールな観点から明らかにするために実験及び数値解析を行った。ハイドロゲルの抵抗低減効果について流体力学的な観点から乱流中の渦構造との関係から明らかにし、抵抗低減率を向上させるための塗膜形成法を提案した。本研究で成果を実船での塗装に活かすことによって、大型船舶からのCO2削減、燃費性能の向上が期待できる。