Onset of pulsing in two‐phase cocurrent downflow through a packed bed

In cocurrent downflow of a gas and a liquid through a packed column, a transition from trickling flow to pulsing flow is observed as one increases the flow rates. A simple macroscopic model for the two‐phase flow is analyzed to examine whether this regime transition should be viewed as the loss of stability of a steady state or the loss of existence of any solution for the steady‐state equations of motion. The former appears to be a more reasonable interpretation and an explicit algebraic criterion for the onset of pulsing is presented.