This study numerically investigates the spreading and retracting dynamics of Janus drops on the inner surfaces of cylinders using the Volume of Fluid method. The results indicate that increasing surface curvature enhances spreading in the axial direction and promotes the detachment of the low-viscosity water component, particularly under conditions of high viscosity ratio and Weber number. A regime map is constructed to identify the critical conditions for separation, revealing that surfaces with intermediate curvature exhibit higher separation efficiency compared to those with high curvature. The temporal evolution of axial momenta in the x and z directions highlights the role of viscosity contrast in inducing asymmetric deformation. A scaling law for residence time is proposed as a function of Weber number, which aligns well with simulation results in the high Weber number regime. These findings provide fundamental insights for optimizing surface curvature and fluid composition to enhance drop separation and may benefit applications such as selective liquid extraction, surface cleaning, and microfluidic manipulation.

In winter, electric power facilities such as solar panels, substations, power towers, and power lines suffer from freezing or ice accumulation problems due to exposure to harsh external environments. These problems result in unstable power supply, high maintenance costs, and severe economic and social losses. To address these problems, diverse anti-icing or deicing techniques including physical, thermal, and chemical approaches have been developed. However, these conventional approaches have limitations such as requirements for additional external energy, environmental toxicity, and low applicability. Recently, novel anti-icing surfaces based on unique drop bouncing dynamics have been developed by mimicking nano/micro-structures of natural systems. These anti-icing surfaces have attracted attention due to their high energy efficiency and environmental friendliness. It has been found that the superhydrophobic surfaces with specific nano/micro-structures can effectively remove the water droplets before the formation of ice nucleation by minimizing contact area and contact time between the droplets and the surface, thereby demonstrating excellent anti-icing properties. This review introduces recently developed anti-icing techniques based on the drop bouncing dynamics, and briefly describes the future direction of the anti-icing technology for stable power supply.