Multi-scale cross entropy analysis for inclined oil–water two-phase countercurrent flow patterns

The flow of an oil–water two-phase fluid in an inclined pipe exhibits fundamentally different behaviors to that of a vertical two-phase flow, especially the flow commonly presents complex countercurrent flow structure due to the influence of gravity. The understanding of inclined oil–water flow is of important significance for flow measurement and production optimization. We using multi-scale cross entropy (MSCE) analysis investigate the nonlinear dynamics of inclined water-dominated oil–water two-phase flow patterns which are Dispersion oil-in-water-Pseudoslugs (D O/W PS), Dispersion oil-in-water-Countercurrent (D O/W CT) and Transitional Flow (TF). We find that the rate of low-scale cross entropy can effectively identify flow patterns, and the high-scale cross entropy can represent their long-range dynamics. The research results show that the multi-scale cross entropy analysis can be a helpful tool for revealing nonlinear dynamics of inclined oil–water two-phase flow in terms of microscopic and macroscopic views.

► We test both algorithms on typical nonlinear dynamic systems. ► Multi-scale Cross entropy shows excellent anti-noise ability. ► Both methods can identify flow patterns and represent inner characteristics. ► For low scales increasing entropy indicates the complexity of flow patterns. ► For high scales stable entropy indicates stable macroscopic dynamic of flow patterns.