A numerical investigation into the effects of inclination on the development of slugging in channel flow

Abstract

Gas-liquid pipe flows are extremely important in many industries, one of which is the oil/gas industry which is where the motivation for this work comes from and where the transition to a slug flow regime is undesirable. It has been shown that, for constant inclination, two steady-state solutions exist which result in a saddle-node bifurcation and means that there are no uniform steady state solutions for sufficiently uphill flow [5]. We will provide a brief overview of the model — a hydraulic model for turbulent, two-layer, gas–liquid flow with gas velocity much greater than liquid velocity, in a horizontal channel —and steady-state analysis covered by Giddings & Billingham [5] before extending their numerical investigation into the effects of inclination on the development of slugging. This leads to the discovery that an uphill section followed by a horizontal section produces larger roll waves in the horizontal section than would otherwise be formed. This is of particular importance as subsea natural gas pipelines must travel uphill as they leave the sea before travelling across land which may result in larger roll waves, and potentially slugs, forming. Further, we will demonstrate, numerically, the likely formation of a slug at any point where the angle of inclination of the channel is anywhere equal to that of the saddle-node bifurcation angle.