Molecular Dynamics Investigation of Liquid and Vapor Interactions Near an Evaporating Interface: A Theoretical Genetics Perspective

K Montazeri and S Hao and MJA Qomi and Y Won, ADVANCED THEORY AND SIMULATIONS, 3, 2000017 (2020).

DOI: 10.1002/adts.202000017

Understanding phase transition between the liquid and gaseous states has gained significant interest, and has been ubiquitously observed in many places ranging from natural systems to water-energy nexus and thermal management applications. Phase transition phenomena at liquid-vapor interfaces are greatly governed by intermolecular-level kinetics, which requires the use of empirical parameters in continuum-level relations to explain the discrete nature of molecular particles. Despite its significance, it has been a great challenge to find detailed expressions of empirical parameters such as accommodation coefficients, which represent the probabilities for phase transition of liquid or vapor molecules at the interface. Here, direct statistical measurements of accommodation coefficients are reported by tracking the trajectories of liquid and vapor molecules in molecular simulations. The measurements reveal that evaporation and condensation coefficients are different by approximate to 50%, whereas they have been assumed to be equal in most previous studies. Then, the indirect measurement method is studied from a perspective of theoretical genetics based on the diffusion approximation. A good agreement between two approaches suggests that diffusion approximation can contribute to provide empirical parameters with a cost-effective method.

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