Review of Applicability of the One-dimensional Two-fluid Model to the Prediction of Wave Growth and Slug Evolution in Horizontal Pipes

Abstract

The paper reviews recently made advances in the application of the two‐fluid model to the numerical simulation of wave growth and ensuing development of slug flow in horizontal pipes. Results from the well‐established linear stability analysis of the governing equations are examined first. Such analyses show that under certain conditions, perturbations in stratified flow can grow into waves that may eventually develop into slugs; this has been verified by numerical computations. These computations can be followed through the growth phase of the waves to the evolution of continuous trains of slugs; this technique is called “slug capturing.” Such a capability provides a powerful tool for predicting slug flow and its characteristics like slug length and frequency in an automatic manner. This technique has been validated extensively against measurements and was found to give remarkably good agreement for slug characteristics. An interesting and remarkable finding is the ability of the model to predict the statistical nature of slug growth and development; the question of how a simple one‐dimensional model could reproduce the real stochastic nature of slug flow has not been addressed before. In this paper it is explained by examination of the predicted wave‐growth rates over the wave length spectrum of the original perturbations.