Critical conditions for enhancing close-contact melting on superhydrophobic surfaces

Close-contact melting (CCM) is a technique that is employed widely in a variety of industrial contexts, including glacier drilling, food processing, and thermal energy storage. CCM is initiated by the application of force to compress an unmelted solid against a heated surfaces, resulting in the formation of a thin film flow between them. The use of superhydrophobic surfaces is often regarded as a means of reducing drag force and enhancing liquid transport. However, the presence of trapped air within the structures of these surfaces also introduces additional thermal resistance. It is currently unclear whether superhydrophobic surfaces can accelerate the melting rate for CCM.



This study employs a theoretical approach to examine the dynamics of close-contact melting (CCM) on gas-trapped superhydrophobic surfaces, taking into account the effects of geometrical confinement and the gas-liquid meniscus resulting from the thinness of the film and the pressure exerted on it. Based on numerical solutions for velocity and temperature slip lengths, we demonstrate significant differences in slip lengths with and without confinement and meniscus effects. Using numerical results and asymptotic solutions, we construct a phase diagram for this problem and identify the critical conditions for enhancing close-contact melting on superhydrophobic surfaces.