<p> Numerical study explores the impinging and separation dynamics of Janus drops on the inner surface of the cylinder decorated with a ridge, using the Volume of Fluid method. The analysis focuses on how ridge-induced asymmetry and geometric confinement influence momentum evolution in the axial, circumferential, and vertical directions, which govern the separation and residence time of the low-viscosity component. Numerical results show that increasing curvature enhances asymmetry and promotes separation, with the critical Weber number decreasing significantly as curvature increases. A theoretical model that accounts for asymmetric rim retraction and spreading geometry successfully captures the residence time trends observed in the simulations, revealing a scaling behavior with both the Weber number and the curvature ratio between the cylinder and the drop. The results reveal that separation efficiency and residence time can be effectively tuned by adjusting impact inertia, viscosity contrast, and surface curvature, offering new insights for the control of multiphase drop dynamics via substrate design.</p>