Shedding of Oil Drops From a Glass Surface Due to Water Cross Flow

The shedding of silicon oil drops from a glass surface due to water cross flow is presented. The surface was placed inside a rectangular channel filled with water, and on top of the surface a drop of given size was placed. Various sizes of the drops were used for the experiment. The flow of water was gradually increased so that the drop sheds when the drag and the adhesion balance each other. The cross-flow velocity of water at that point was called the critical velocity. The critical velocity was found to decrease with increase in drop size. The contact lengths and heights were found to increase with the drop size. The increase in the contact length increases the adhesion, but the increase in height raises the drag applied. Hence the critical velocity decreases.