RAPID: Flow Asymmetry in Human Breathing and the Asymptomatic Spreader

病毒在呼吸和说话过程中的气溶胶传输，在人们的社会交往中很常见，但在很大程度上还没有研究。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。新冠肺炎的迅速传播突显出，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。最近来自医院甚至媒体的证据表明，应该重新研究这一运输途径的流体动力学。这项研究的重点将是量化对话或附近相遇期间与言语和呼吸相关的复杂流动，并展示粒子如何在个体之间传播。从这项工作中获得的理解将提供可行的缓解策略，以减少无症状人群的传播。这些结果在短期内可能是有用的，因为它提供了减少潜在的病毒传播和未来感染的途径。这项研究将展示说话或简单呼吸过程中呼气和吸气之间的内在结构流差异如何成为病原体传播的一种有效而又意想不到的传输机制。研究结果将量化这种传播的一个重要方面，就新冠肺炎而言，这种传播与相对密切的社交互动中的无症状携带者有关。关于病毒传播的这一重要主题的定量描述在很大程度上没有出现在流体力学和传输现象文献中，甚至更普遍地，在公共卫生的定量研究中也没有。利用流动可视化和数值模拟，研究将破译呼吸和说话过程中个体头部附近的流体动力学，以及对潜在传播(附近人吸入颗粒物)至关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物与附近人吸入的颗粒物的比例，作为他们分离距离的函数。通过这些方式，这项研究将揭示与简单的人类活动相关的简单但基本的运输机制，即呼吸和说话，这种机制可以推广到许多病原体，并有助于确定通过气雾剂传播疾病的潜在缓解策略。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.