The Atomic Detail of Evaporating Menisci

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ABSTRACTNational Science FoundationProposal Number: CTS-0437583Principal Investigator: Freund, Jonathan B.Affiliation: University of Illinois-Urbana-ChampaignProposal Title: The atomic detail of evaporating menisciEvaporation that takes place at the junction where a solid-liquid-vapor co-exist, the so-called tri-junction, plays a critical role in multi-phase heat and mass transfer. In nucleate and other phase-change heat transfer applications, it accounts for a significant fraction of the overall evaporative mass and heat flux. Since the junction is frequently the endpoint of a thin liquid film on a surface, its behavior alters the dynamics of the entire thin film. Modeling of evaporation and boiling is primarily handled using continuum models with empirical closures. Promising continuum models of the tri-junction have been developed that couple for example hydrodynamics to kinetics. Agreement with experiment has been encouraging. It is generally known that in the thinnest liquid regions such as evaporating menisci, additional molecular effects will become important. This project will undertake the first ever atomistic simulations of evaporating menisci near solid-liquid -vapor-tri-junctions in order to observe their atomic detail. In the tri-junction, sub-scale focused atomistic simulations will be performed to investigate the local flow and fluid properties used in the unified meniscus model, namely viscosity, surface tension, thermal conductivity, and evaporation kinetics. The atomistic simulations will be interpreted in the context of a continuum lubrication model previously developed by the PI, and improvements to the overall meniscus model will then be made and validated against the full-scale atomistic simulations of the evaporating meniscus. The award has been funded by the Thermal Transport and Thermal Processing Program of the Chemical and Transport Systems Division.