CAREER: Impact of Inlet Conditions on Interfacial Instability and Spray Formation: High-Fidelity Simulation, Characterization, and Sub-Grid Modeling

一个有效的模拟，可以精确地预测喷雾形成的过程将是非常有益的各种重要的应用，如内燃机，喷雾冷却，薄膜制造。推进喷雾形成模拟的两个基本障碍是：1）缺乏对入口条件对液体不稳定和破碎的影响的全面理解; 2）可以捕获所有物理尺度的高保真模拟的极端计算成本。该项目旨在通过高保真模拟来描述入口条件对喷雾形成的影响，从而解决这两个挑战。建议的工作将集中在平面气流雾化器形成的喷雾，以更好地了解基本的流体动力学。在该项目中获得的喷雾形成过程的物理见解将有助于工程师开发新技术来控制喷雾特征。该教育计划将与贝勒的梅伯恩博物馆的NSF资助的门户网站的公共计划和学习体验（LEx）实验室的区域12教育服务中心合作开发。拟议项目的具体目标是：1）通过高保真度模拟来表征入口气体湍流、气体流入速度的不对称性2）建立了一种基于液体结构拓扑离散化的亚网格模型;以及3）根据我们的模拟和建模研究创建教育活动，以激励K-12学生，包括7-12年级的学生和身体有缺陷的学生，考虑STEM教育和职业途径。以前的研究一般限于进口条件的基本特征，如平均速度分布，而更精细的方面，如进口湍流和进口流动不对称性通常被认为是次要的。这一假设受到了最近实验的挑战，本项目将系统地研究这一假设。该研究将全面了解入口条件对界面不稳定性和喷雾形成的影响。本文将利用计算机图形学中广泛应用的网格化方法，建立一种新的喷雾形成亚网格模型。表面，曲线和点骨架，代表微尺度的液体片，细丝，和液滴形成的雾化，将提供一个框架来模拟未解决的动态，变形，和这些液体结构的分裂。新模型的使用将显著降低喷雾形成数值模拟的计算成本。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

An efficient simulation that can precisely predict the process of spray formation would be of great benefit to a variety of important applications such as combustion engines, spray cooling, and thin-film fabrication. Two fundamental barriers in advancing simulation of spray formation are 1) the lack of a comprehensive understanding of the effects of inlet conditions on the destabilization and breakup of liquids; and 2) the extreme computational cost of a high-fidelity simulation that can capture all the physical scales. This project aims to tackle these two challenges by characterizing the impact of inlet conditions on spray formation through high-fidelity simulation. The proposed work will be focused on sprays formed by planar air-blast atomizers to better understand the fundamental fluid dynamics. The physical insights of spray formation processes obtained in the project will assist engineers in developing new techniques to control spray features. The educational plan will be developed in collaboration with Baylor's Mayborn Museum's NSF-funded Portal to the Public program and the Learning Experience (LEx) Labs of the Region 12 Educational Service Center.The specific objectives of the proposed project are: 1) to characterize through high-fidelity simulation the effects of inlet gas turbulence, asymmetry in the gas inflow velocity, and geometry of gas inlets on interfacial instability and spray formation; 2) to establish a novel sub-grid model based on topological skeletonization of liquid structures; and 3) to create educational activities based on our simulation and modeling research to inspire K-12 students, including those in grades 7-12 and those with physical limitations, to consider a STEM education and career pathway. Former studies were generally limited to basic features of inlet conditions, such as the mean velocity profile, and finer aspects such as inlet turbulence and inlet flow asymmetry are usually assumed to be secondary. This assumption has been challenged by recent experiments and will be systematically examined in this project. The research will provide a comprehensive understanding of the impact of inlet conditions on interfacial instability and spray formation. The skeletonization method, which is widely used in computer graphics, will be employed to develop a novel sub-grid model for spray formation. The surface, curve, and point skeletons, representing micro-scale liquid sheets, filaments, and droplets formed in atomization, will provide a framework to model the unresolved dynamics, deformation, and breakup of these liquid structures. The use of the new model will significantly reduce the computational cost of numerical simulation of spray formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.