Sub-regimes of horizontal gas–liquid intermittent flow: State-of-the-art and future challenges

Based on the shape of the interface elongated bubble/liquid slugs and the liquid slugs’ aeration, the horizontal intermittent flow can be divided into three sub-regimes including plug (PG), Less Aerated Slug (LAS) and Highly Aerated Slug (HAS) flows. These flow sub-regimes were observed from experiments performed using air–water mixture and small pipe diameters. This paper presents an analysis of the results obtained with the aim of constituting the state-of-the-art of this sub-regimes classification.

The critical review, of the current state of knowledge, has led to the conclusion that the subdivision of intermittent flow into sub-regimes may provide a better means of apprehending, understanding and advancing in the modelling of slug parameters, Interfacial Area Concentration, Pipeline Integrity Management, intermittent flow behavior across singularities, as well as for the development of more realistic mechanistic models. The acquired knowledge can be beneficial for petroleum and gas, nuclear and chemical engineering industries among others.

Finally, based on the presented state-of-the art, some recommendations are given for future works using this approach. These reflection paths will allow improving our comprehension on intermittent flow, promoting the development of more robust models.