The Effect of Interfacial Waves on the Transition to Slug Flow

It has been proposed by the authors that the transition to slug flow depends on the growth of waves in the two-phase flow and thus may predict if the laws of wave growth in closed channel are known. In this work, this proposition is tested by examining the highest waves and the transition to slug flow for air and water, air and water with surface tension reduced by addition of surface-active agents, air and water with increased viscosity by addition of corn syrup and air and ethanol. In each case it is found that the predicted transition to slug flow agrees well with experimental data. Neither a lower surface tension nor a higher viscosity has any effect on the transition to slug flow, but the use of surface active agents reduces the wave growth rate and causes the transition to slug flow to shift to higher gas velocities.