Theoretical and numerical investigation of particle-vortex interaction in semi-dilute dusty flows

尘流在自然界和工程应用中都很常见。沙尘暴和火山灰是自然界中广泛发生的例子。在工程应用中，粉尘流可能代表着重大的操作和安全挑战。旋转的飞机在接近地面时扬起的尘埃云可能会降低能见度，损坏叶片，并导致发动机退化。众所周知，由行星着陆模块上的推进器扬起的尘埃云会干扰飞船上的遥测，产生静电危害，并导致着陆表面不平整。由于对微米级颗粒的反馈力如何改变载流子流动的理解有限，预测半稀释尘埃云的演变，如在工程中遇到的，仍然是一个挑战。拟议的研究将建立半稀释尘云的预测模型，支持行星着陆模块的开发，依靠机器人直升机探索和收集土壤样本的科学任务，以及为在沙漠条件下运行的旋转飞机制定缓解战略。该奖项还旨在激励来自服务欠缺社区的高中生接受STEM教育。这些学生将在亚利桑那州立大学的实地考察中获得实践经验，作为学习模块的一部分。本奖项提出的研究解决了人们对半稀释粉尘流中旋涡动力学知之甚少的问题，其中悬浮粉尘颗粒对流体的反馈力导致与传统无颗粒涡旋明显不同的生长和配对过程。该奖项将回答以下问题：1)在双向耦合下，分散惯性粒子调制孤立涡旋管的机制是什么？2)粒子惯性如何影响粒子涡旋不稳定性？3)在半稀尘流中，常规涡对合并是如何变化的？这些问题将通过理论和数值分析的结合来解决，即线性稳定性分析和高保真的欧拉-拉格朗日模拟。考虑到颗粒相的特征，包括斯托克斯数、体积分数、质量载荷和密度比，将使用标度定律来表征颗粒负载的旋涡结构的命运。该奖项反映了美国国家科学基金会的法定使命，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。

Dusty flows are common in nature and engineering applications. Sand storms and volcanic ash are among examples widely occurring in nature. In engineering applications, dusty flows may represent significant operating and safety challenges. Dust clouds kicked up by rotary aircrafts in ground proximity may reduce visibility, damage blades, and lead to engine degradation. Dust clouds kicked up by thrusters on planetary landing modules are known to interfere with on-board telemetry, create electrostatic hazard, and lead to uneven landing surfaces. Due to limited understanding of how the feedback force from micron-sized particles alters the carrier flow, predicting the evolution of semi-dilute dust clouds, such as those encountered in engineering, remains a challenge. The proposed research will enable predictive models of semi-dilute dust cloud, support the development of planetary landing modules, science missions relying on robotic helicopters to explore and collect soil samples, and the development of mitigation strategies for rotary aircrafts operating in desert conditions. This award also aims at inspiring high-school students from underserved communities to pursue STEM education. These students will get hands-on experience as part of a learning module that will be delivered to them during a field trip to Arizona State University. The proposed research in this award addresses poorly understood vortex dynamics in semi-dilute dusty flows where the feedback force by suspended dust particles on the fluid leads to growth and pairing processes remarkably different from those of conventional particle-free vortices. This award will answer the following questions: 1) What are the mechanisms by which dispersed inertial particles modulate an isolated vortex tube under two-way coupling? 2) How does particle inertia affect particle-vortex instabilities? 3) How does the conventional vortex-pair merger change in semi-dilute dusty flows? These questions will be addressed using a combination of theoretical and numerical analyses, namely, Linear Stability Analysis, and high-fidelity Euler-Lagrange simulations. The fate of particle-laden vortical structures will be characterized using scaling laws that take into account the characteristics of the particle phase, including Stokes number, volume fraction, mass loading, and density ratio.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.