Abstract
Recently, it has noticed the flow characteristics of a liquid on a highly water -repellent wall that the gas-liquid interface occurs near the solid surface. We reported the drag reduction of flow around a circular cylinder with a highly water-repellent wall, that fluid slip occurred at the wall and the separation point moved to the downstream direction comparing with the smooth solid surface circular cylinder. The purpose of this study is experimentally to clarify the motion of a highly water-repellent sphere in Newtonian Fluids. Experiments were carried out the measurement of the fall velocity by the falling sphere experiment. The drag coefficient of a highly water-repellent sphere increases comparing with that of the smooth sphere. It can be considered the buoyancy increases in the effect of the gas phase of the sphere surface. The experimental results obtained in this study can be applied to prevent the precipitation of solid particle by suspensions.
