Dynamics of Janus drop splitting on inclined surfaces

This study investigates the impact dynamics and splitting behavior of Janus drops on inclined surfaces using a volume of fluid multiphase flow model. The simulation domain consists of compound drops composed of low- and high-viscosity fluids, representing water and a glycerin–water mixture, respectively. This study explores the effects of viscosity ratio, impact velocity, and surface inclination on the asymmetrical deformation and detachment of the low-viscosity component. Numerical cases are conducted for different Ohnesorge number ratios and Weber numbers at inclination angles up to 45°. Results show that increasing the viscosity contrast and tangential inertia promotes the alignment and separation of the water part, with separation ratios reaching up to 0.9. A regime map is constructed to illustrate the critical conditions for effective separation. The findings suggest that tuning the viscosity contrast and substrate inclination provides a practical route for enhancing directional detachment in multiphase systems, relevant to applications such as liquid separation and surface cleaning.