RAPID: Flow Asymmetry in Human Breathing and the Asymptomatic Spreader

在呼吸和说话过程中的病毒气溶胶运输，在人们的社会交往中很常见，在很大程度上没有研究。 最近有重要证据表明，这些流动背后的流体动力学可能在新冠肺炎的传播中发挥重要作用。新型冠状病毒肺炎（COVID-19，即2019冠状病毒病）的迅速蔓延凸显出，在没有疫苗的情况下，缺乏有效的指导方针和缓解策略来减少传染性病毒的影响。最近来自医院，甚至新闻界的证据表明，这种运输途径的流体动力学应该重新调查。这项研究的重点将是量化与谈话或附近相遇期间的语音和呼吸相关的复杂流，并显示个体之间的粒子传输是如何发生的。从这项工作中获得的理解将提供可操作的缓解策略，以减少无症状人群的传播。这些结果可以在短期内通过提供途径来减少潜在的病毒运输和未来的infection.This研究将显示如何在讲话或简单呼吸过程中呼气和吸气之间的固有结构性流动差异可能是一个强大的但未被怀疑的病原体传播的运输机制。研究结果将量化这种传播的一个重要方面，在新冠肺炎病例中，这与相对密切的社交互动中的无症状携带者有关。围绕病毒传播的这一重要主题的定量表征在很大程度上缺乏流体力学和传输现象的文献，甚至更普遍地缺乏公共卫生的定量研究。使用流动可视化和数值模拟，调查将破译呼吸和说话期间个人头部附近的流体动力学，以及对潜在传播（附近人员吸入颗粒）重要的相应环境混合。这种方法将允许量化一个人呼出的颗粒被附近的人吸入的分数，作为其分离距离的函数。通过这些方式，这项研究将揭示与简单人类活动相关的简单而基本的运输机制，即，呼吸和说话，这可以推广到许多病原体，并有助于确定潜在的缓解战略，疾病传播的气溶胶。这一奖项反映了NSF的法定使命，并已被认为是值得支持的评估使用基金会的知识价值和更广泛的影响审查标准。

Aerosol transport of viruses during breathing and speaking, as is common during social interactions of people, is largely unstudied. There is significant recent evidence that the fluid dynamics behind these flows may play a significant role in the spread of Covid-19. The rapid spread of Covid-19 highlights the lack of effective guidelines and mitigation strategies for reducing the impact of a contagious virus in the absence of a vaccine. Recent evidence from hospitals, and even the press, suggests that the fluid dynamics of this transport pathway should be re-investigated. The focus of this research will be to quantify the complex flows associated with speech and breathing during a conversation or nearby encounter and show how transmission of particles between individuals occurs. The understanding gained from this work will provide actionable mitigation strategies to reduce transmission from asymptomatic people. These outcomes can be useful in the short term by offering routes to reducing potential viral transport and future infections.This research will show how the inherent structural flow difference between exhalation and inhalation during speech or simple breathing could be a potent yet unsuspected transport mechanism for pathogen transmission. The results will quantify an important aspect of this transmission, which in the case of Covid-19 is associated with asymptomatic carriers during relatively close social interactions. The quantitative characterization of this important topic surrounding viral transmission has largely been absent from the fluid mechanics and transport phenomena literatures, and even absent more generally from quantitative studies of public health. Using flow visualization and numerical simulations, the investigation will decipher the fluid dynamics in the neighborhood of the head of an individual during breathing and speaking, and the corresponding environmental mixing important to potential transmission (inhalation of particles by a nearby person). This approach will allow quantifying the fraction of particles exhaled by one person that are inhaled by a nearby person as a function of their separation distance. In these ways, the research will shed new light on a simple yet fundamental mechanism of transport associated with simple human activities, i.e., breathing and speaking, which can be generalized to many pathogens and aid in the identification of potential mitigation strategies for disease transmission by aerosols.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.