Visibility graph analysis of fluid flow signals

Visibility graphs have established themselves in recent years as being particularly suitable and flexible for analyzing signals measured from complex natural and artificial systems. Oil-water two-phase flow as a complicated fluid flow is one of the most complex systems. In this paper, we employ visibility graph to analyze the signals measured from experiment two-phase flow. We first introduce the inclined oil-water two-phase flow experiment and data acquisition. Then we present the algorithm for constructing visibility graphs from signals. Finally, we infer and analyze visibility graphs from signals measured under different fluid flow conditions. The results indicate that the combination parameters of network degree are sensitive to the transition among different flow patterns, which can be used to distinguish and characterize different oil-water two-phase flow patterns. In this regard, visibility graph could be a useful tool for processing experimental signals.