The Atomic Detail of Evaporating Menisci

国家科学基金会建议编号：CTS-0437583主要研究人员：Freund，Jonathan B.隶属：伊利诺伊大学厄巴纳香槟分校建议标题：蒸发弯月面的原子细节发生在固-液-汽共存的交界处，即所谓的三重交界处，在多相传热和传质中起关键作用。在核化和其他相变换热应用中，它占总蒸发质量和热通量的很大一部分。由于结点通常是表面上的薄液膜的终点，它的行为改变了整个薄膜的动力学。蒸发和沸腾的模拟主要使用带有经验闭合的连续介质模型。例如，将流体力学与动力学相结合的三结点连续介质模型已经被开发出来。与实验的一致是令人鼓舞的。众所周知，在最薄的液体区域，如蒸发的半月板，额外的分子效应将变得重要。该项目将首次对固体-液体-蒸汽-三结点附近蒸发的半月板进行原子模拟，以观察它们的原子细节。在三结点中，将进行亚尺度聚焦原子模拟，以研究统一的半月面模型中使用的局部流动和流体性质，即粘度、表面张力、导热系数和蒸发动力学。原子模拟将在PI先前开发的连续介质润滑模型的背景下进行解释，然后将对整个半月面模型进行改进，并对照蒸发的半月面的全尺寸原子模拟进行验证。该奖项由化学和运输系统部门的热运输和热加工项目资助。

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.