RAPID: Fluid Dynamic Driving Mechanisms of Airborne Pathogen Transmission and Control

COVID-19等空气传播病原体已造成大规模感染、死亡、卫生系统超载和严重的经济损失。这种空气传播途径可能与人类自然呼吸功能（如打喷嚏、咳嗽、说话和呼吸）喷射的飞沫有关。即使在保持社会距离和戴口罩的情况下，与医院、杂货店、交通工具和其他必要的密闭工作场所相关的一些基本功能也会迫使相互作用并加剧病原体的传播。减少空气传播病原体的一种潜在方法是减少由人体呼吸功能形成的小飞沫的数量。众所周知，小水滴（如雾、薄雾等）可以长时间保持悬浮状态。这种飞沫可以长时间传播病原体。由于大的液滴（如雨）容易从空气中落下，这些液滴中的病原体不易受到空气传播途径的影响。这项研究的目的是改变宿主的流体特性，使在人体呼吸功能期间形成的液滴保持较大，传播距离较短，并降低空气传播的倾向。该项目旨在量化在人体呼吸功能过程中，当宿主唾液特性发生改变时形成的液滴特征。与改变宿主流体特性有关的简单流体相关的解决方案，如配方糖果（含片/口香糖/糖果），将改变唾液液滴的分解模式，导致更大的液滴移动更短的距离并落下。目的是了解流体特性如何减少与病原体空气传播路径相关的指标。在人体呼吸功能过程中，液滴的形成是由脉冲湍流射流驱动的复杂过程，具有许多潜在的界面不稳定性。这些过程尚未从改变宿主鼠尾草液体性质的角度进行研究。该项目将利用实验和数值预测相结合的方法来开发这一知识缺口，主要围绕回答三个具体研究：(i)了解粘度和表面张力在液滴特性中的作用，（ii）评估唾液充气如何改变液滴特性，以及（iii）确定减少空气传播同时保持人体舒适的安全化合物。在解决这些科学问题时，这项工作旨在开发一种新工具，以减少COVID-19（和其他空气传播病原体）的传播。这项工作旨在（通过新闻、快速出版物和专业会议）在一个时间表内向公众、科学家和工程师通报发达的科学，从而实现支持2020年COVID-19大流行的产品开发和大规模实施。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。

Airborne transmitted pathogens such as COVID-19 have caused large scale infections, death, health system overloads, and severe economic damage. Such airborne transmission paths can be associated with droplets ejected from natural human respiratory functions such as sneezing, coughing, speaking, and breathing. Even in the context of social distancing and face masks, there are several essential functions associated with hospitals, grocery stores, transit, and other essential confined workplaces that force interactions and fuel pathogen transmission. One potential method to reduce the transmission of airborne pathogens is to reduce the number of small droplets formed from the human respiratory function. It is generally known that small droplets (such as fog, mist, etc.) can remain suspended for long time periods. Such droplets enable transmitting pathogens for long time periods. Since large droplets (such as rain) are prone to fall from the air, pathogens in these droplets are less susceptible to airborne transmission paths. The aim of this research is to alter the host’s fluid properties such that droplets formed during human respiratory functions remain larger, travel shorter distances, and fall reducing the propensity for airborne transmission. The project seeks to quantify the droplet character formed during human respiratory function when the host’s saliva properties are altered. Simple fluids-related solutions associated with altering the fluid properties of the host such as formulated confections (lozenges/gum/candy) will change saliva droplet breakup modes resulting in larger droplets that travel shorter distances and fall. The aim is to understand how fluid properties can reduce metrics associated with a pathogen’s airborne transmission path. During the human respiratory function, droplets are formed through complex processes driven by a pulsed, turbulent jet with many underlying interfacial instabilities. These processes have not been studied from the aspect of altering the host’s salvia fluid properties. The project will develop this knowledge gap using a combination of experiments and numerical predictions oriented around answering three specific studies: (i) Understanding the role of viscosity and surface tension in droplet characteristics, (ii) Evaluating how aerating saliva alters droplet characteristics, and (iii) Determining safe compounds that reduce airborne transmission while remaining comfortable to a person. In addressing these scientific questions, this effort aims to develop a new tool to reduce the transmissibility of COVID-19 (and other airborne pathogens). The effort is tailored to inform the public, scientists, and engineers (through press, fast-track publications, and professional meetings) of the developed science within a timeline that enables product development and wide-scale implementation that supports the 2020 COVID-19 pandemic.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.