Influence analysis of the closing parameters in the unit cell model for gas-liquid flows in the intermittent pattern

Abstract

A succession of liquid pistons (aerated or non-aerated) and elongated gas bubbles parallel with a thin liquid film that repeats itself over the pipe in a non-periodic way describes the intermittent or slug flow. These flows can occur in a steady state considering the unit cell concept. Thus, the hydrodynamic parameters of this kind of flow can be estimated using several models developed based on this concept. In closing these models, several empirical correlations help predict essential parameters, which depend on the primary characteristics of the flow and the pipe. In this context, this work aims to numerically analyze the performance of one of these more complete models, considering several correlations, both for unit cell frequency and slug liquid holdup. A computational code written in MATLAB gave the solution of the unit cell model with various empirical correlations to estimate the closure parameters in this work. The governing equation of the model was solved using the finite difference method. The numerical results for the pressure gradient were compared with experimental data from the literature to demonstrate which combinations of correlations were more satisfactory, validating the model implemented computationally.