AbstractIn this work, the water holdup and slippage for oil and water mixture flows in horizontal, vertical, and inclined pipes have been investigated. A large group of experimental data was collected from 21 different sources covering the whole range of inclination angles from −90° to 90° to reveal the holdup characteristics and develop the drift velocity model. The results show that in horizontal flows the water holdup is dependent to the flow pattern, and yet in vertical flows the water holdup is similar to the input one and the flow direction shows a few influences on the holdup. In inclined flows, the Froude numbers are relatively independent of inclination angles when the angles are greater than 30°. Therefore, the changes of water holdup in the pipe with small inclination angles are more severe than those with large inclination angles. In addition, a satisfactory agreement between predicted and experimental holdups substantiates the general validity of the proposed drift velocity correlation for oil and water flows, especially for those with large inclination angles.