Construction of Guideline for Surface Nanobubble Controlling Based on Microscopic Mechanical Balance at Three-Phase Contact Line

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14098
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: University of the Ryukyus
• Principal Investigator: Nagashima Hiroki 琉球大学, 工学部, 助教 (00759144)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: ナノバブル / 分子動力学法 / 三相界線 / ヤングの式 / 力学的バランス / 濡れ性 / 壁面形状 / 壁面温度

Outline of Final Research Achievements

In order to construct a guideline for the control of nanobubbles on solid surfaces, the microscopic mechanical balance at the three-phase interface was analyzed using molecular dynamics (MD). The mechanical balance was analyzed by comparing the apparent contact angle of nanobubbles computed from the density distribution with the contact angle derived from Young's equation. Each surface tension in Young's equation was calculated by dividing the computational domain into small areas and calculating the pressure in those areas using the MD method. The analysis was performed by varying the wettability of the solid wall, the shape of the wall (e.g., unevenness), and the temperature of the wall. The results suggest that the shape of nanobubbles can be controlled by the wettability of the wall, the wall shape, and the wall temperature.

Free Research Field

分子熱流体工学

Academic Significance and Societal Importance of the Research Achievements

本研究成果の学術的意義は、実験では観測が難しい固体壁面上のナノバブルの三相界線の微視的力学的バランスを分子動力学法により解析し、壁面の濡れ性、壁面形状、壁面温度により三相界線の力学的バランスがどのように変化するかを明らかにしたことである。本研究により得られた知見に基づいて、壁面特性により三相界線の力学的バランスをコントールすることで、固体壁面上のナノバブルの形状を制御できると考えられる。固体壁面上のナノバブルは流体の摩擦低減効果，固体表面の伝熱制御，沸騰の初期現象として工学的に重要であり，特に熱工学分野における本研究成果の社会的意義は大きいと考えられる。