Study on Taylor slug formation process and leakage flow characteristics in curved T-microchannels

In liquid–liquid multiphase microflows, Taylor slugs are crucial for controlling interfacial mass transfer and maintaining flow stability. While slug formation and motion in straight microchannels have been extensively studied, the influence of channel curvature on slug dynamics remains insufficiently explored. In this study, we systematically investigate the formation and transport behavior of Taylor slugs in curved microchannels with rectangular cross sections. A detailed force analysis reveals that slug formation undergoes three distinct stages: rapid elongation, slowed stretching, and sudden breakup. Compared to straight channels, the curvature-induced Dean flow significantly alters the interfacial evolution and enhances the controllability of slug size and formation frequency, offering a new approach to interface-based mass transfer intensification. We further construct flow regime maps and identify three typical flow patterns—slug flow, long slug flow, and columnar flow—highlighting their regime transitions under different flow conditions. The transport of slugs exhibits strong nonuniformity due to asymmetric pressure fields and interface deformation. More importantly, the coupling relationship among slug length, velocity, and corner leakage flow is clarified through quantitative image analysis and dimensionless correlation. Results show that slugs experience increased outer-wall leakage in curved channels, governed by Dean vortices and radial pressure gradients, while leakage decreases with increasing slug length and dispersed-phase viscosity. Finally, a dimensionless prediction model for slug length is developed by incorporating the effects of flow rate ratio, viscosity, and channel geometry, achieving a prediction error within ±20%. The model enables accurate real-time prediction of slug length at any channel position. This work provides in-depth mechanistic insight into the dynamic behavior of Taylor slugs in curved geometries and lays a solid theoretical foundation for designing efficient microreactors and advanced mass transfer systems.