Column separation is described and investigated in terms of the governing fluid dynamics. The partial differential equations of continuity and momentum, including nonlinear friction losses, are used to mathematically represent the transient movement of liquids in pipes under conditions of both full-pipe and free-surface flows. The complete systems of equations are programmed for numerical simulation of the column-separation phenomenon using a digital computer and the method of characteristics. Theoretical time-pressure information derived from mathematical simulation is compared with the corresponding experimental information obtained from laboratory investigation. Despite higher-than-anticipated energy losses in the prototype flow, the general comparison of the two sets of information is favorable.