Abstract
Skin frictional drag of the gas-liquid two-phase flow is investigated using silicon oil in a horizontal channel. The silicon oil has three characteristics, i.e. stable interfacial property, high viscosity, and low surface tension in comparison to water. The present study is planned to grasp the skin friction characteristics modified with bubbles in the oil. The measurement and the visulization results show increment of the frictional drag by bubbles because of promotion of the laminar to turbulent flow transition. Bubble shapes changing with the transition is also discussed.