Atomization of Liquids in Non-isothermal Environments: Multi-scale Modeling and Simulations

液体的雾化是许多自然现象和技术过程的关键组成部分。然而，由于原子化固有的复杂性和无法通过实验详细观察这些过程，对基本物理过程的详细了解是不完整的。这个项目的重点是通过计算研究来提高对这一现象的理解，在大规模并行计算设施上，数学模型包含了在多个长度和时间尺度上作用的几种力之间的相互作用和竞争。基于水平集方法的高保真气液界面跟踪算法将与小尺度液滴的有效拉格朗日描述相结合。由于表面张力对温度的依赖，将包括热马兰戈尼效应，以及蒸发和潜热的相关效应，目的是研究这些过程在多大程度上影响高惯性流动中液滴的破碎级联。该项目将使对控制雾化过程的物理机制的理解取得突破，并对广泛的应用产生潜在影响。其中最重要的是能源系统，其中节能和低污染发动机的设计取决于空气/燃料混合以实现最佳燃烧，而这反过来又严重依赖于燃料喷射喷射雾化产生的液滴大小分布。这将有助于实现能源独立和环境可持续性的国家目标。其他应用包括气溶胶药物输送，农业喷雾和消防（这里要避免水射流雾化，以增加火焰淬火）。精确的海浪雾化模型，特别是那些与大尺度风暴和飓风有关的海浪产生的浪花和小气泡深入海洋，可以改善天气和气候模型以及温室气体对全球变暖影响的预测。该项目还包括研究生和本科生的跨学科培训。

Atomization of liquids is a key component in many natural phenomena and technical processes. Yet, detailed understanding of the fundamental physical processes is incomplete, due to the inherent complexity of atomization and the inability to experimentally observe the processes in detail. This project focuses on improved understanding of the phenomenon by computational studies, on massively parallel computational facilities, of mathematical models that incorporate the interaction and competition among several forces acting on multiple length and time scales. High-fidelity gas/liquid interface tracking algorithms based on the level-set approach will be combined with efficient Lagrangian descriptions of small-scale liquid droplets. Thermal Marangoni effects due to the temperature dependence of surface tension will be included, along with evaporation and related effects of latent heat, with the intent to examine the extent to which these processes affect the fragmentation cascades of droplets in high-inertia flow.The project will enable breakthroughs in the understanding of physical mechanisms that govern the process of atomization, with potential impact on a broad range of applications. Foremost among these are energy systems, where the design of fuel-efficient and low-polluting engines hinges on the air/fuel mix for optimal combustion, and that in turn depends critically on the droplet size distribution from the atomization of the injected jet of fuel. This will aid in achieving national goals of energy independence and environment sustainability. Other applications include aerosol drug delivery, agricultural sprays, and fire-fighting (here atomization of the water jet is to be avoided for increased flame quenching). Accurate atomization models of waves producing sea spray and small air bubbles driven deep into the ocean by breaking waves, especially those associated with large-scale storms and hurricanes, can lead to improved weather and climate modeling and predictions of the impact of greenhouse gases on global warming. The project also includes the interdisciplinary training of graduate and undergraduate students.