Partial wetting phenomena in an externally driven laning system

Abundant interfacial phenomena in nature, such as water droplets on lotus leaves and water transport in plant vessels-originate from partial-wetting phenomena in equilibrium systems, which can be well described by Neumann’s law. It remains an intriguing question whether similar behaviors exist in non-equilibrium systems. Here we demonstrate the partial-wetting phenomenon in a ternary laning system, which is a typical non-equilibrium system. A phase diagram is constructed in which the relative drift velocities of different components govern the transitions among drying, partial wetting, and complete wetting states. The mechanical balance on the contact lines of the partial-wetting phase described by Neumann’s law is verified. A theoretical picture is proposed to explain the analogy of partial wetting in the laning system to that in the equilibrium system. Wetting phenomena, such as droplets spreading on surfaces, are well understood in equilibrium systems but remain largely unexplored in driven non-equilibrium scenarios. In this work, the authors demonstrate that a ternary laning system exhibits controllable drying and wetting transitions, where the contact angles follow Neumann’s law despite the system being far from equilibrium.