Investigation of transition from annular to intermittent flow in pipes

A new unified model is proposed for the transition from annular to intermit tent pow patterns for the entire range of pipe inclination angles, Experime ntally, it has been observed that the transition from annular pow takes pla ce at a critical void fraction. To obtain a transition boundary equation, c onservation of momentum equations for gas and the liquid film are combined and solved with the critical void fraction. The new model captures the corr ect transition characteristics, agrees favorably,vith experimental pow patt ern data, and performs the best when compared,vith previous transition mode ls. [S0195-0738(00)00601-4].