Identification of coherent structures in horizontal slug flow

Multiphase flow measurement devices are significantly affected by the flow pattern, such as, e.g., slug flow, leading to large uncertainties. In this context, the slug flow pattern in horizontal pipes is investigated with the aim of finding a statistical characterization of the structures in space and time. For this, two different instances of slug flow are analyzed with a snapshot proper orthogonal decomposition and an additional mode coupling algorithm, which provides an energy-ranked mode basis of the underlying coherent structures. For the considered flows, the most energetic mode pair has been identified with the corresponding slugging structures. Thereby, the temporal and spatial information of these mode pairs enables a statistical characterization of the slugs. In this context, a length scale, a dominant frequency, and an energy representation of the slugging structures are obtained from this method.