Simulation of the flow rate transient characteristics of gas-liquid slug flow in horizontal pipeline

A dynamic model for transient slug tracking was developed in which the acceleration pressure drop was considered. This model was implemented with OOP technique and then the front and tail of each slug and long bubble were tracked numerically. This model can correctly predict not only the phenomena of the pressure overshoot above the value of the new steady state and the formation of long slugs when the gas flow rate was increased, but also the phenomena of the pressure undershoot and a short period of stratified flow when the gas flow rate was decreased. From the simulation, it is found that the temporary stratified flow caused by the disappearing of most slugs leads to the pressure undershoot, because the pressure gradient in stratified flow is far less than that in slug flow.