RAPID: Flow Asymmetry in Human Breathing and the Asymptomatic Spreader

在人们的社会交往中，呼吸和说话过程中常见的气溶胶传播病毒在很大程度上没有得到研究。最近有重要证据表明，这些流动背后的流体动力学可能在Covid-19的传播中发挥了重要作用。Covid-19的迅速传播凸显出，在缺乏疫苗的情况下，缺乏有效的指导方针和缓解战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，应该重新研究这种运输途径的流体动力学。这项研究的重点将是量化在谈话或附近相遇时与语言和呼吸相关的复杂流动，并显示个体之间的粒子传播是如何发生的。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。这些结果在短期内是有用的，因为它提供了减少潜在病毒传播和未来感染的途径。这项研究将表明，在说话或简单呼吸过程中，呼出和吸入之间固有的结构流动差异可能是病原体传播的一种强有力但未被怀疑的运输机制。这些结果将量化这种传播的一个重要方面，在Covid-19的情况下，这种传播与相对密切的社交互动中的无症状携带者有关。在流体力学和传输现象的文献中，甚至在公共卫生的定量研究中，对围绕病毒传播的这一重要主题的定量表征在很大程度上是缺失的。利用流动可视化和数值模拟，调查将破译呼吸和说话时个体头部附近的流体动力学，以及相应的对潜在传播重要的环境混合（附近的人吸入颗粒）。这种方法可以量化一个人呼出的粒子被附近的人吸入的粒子的比例，作为他们分离距离的函数。通过这些方式，该研究将揭示与简单的人类活动（即呼吸和说话）相关的简单而基本的运输机制，该机制可以推广到许多病原体，并有助于确定气溶胶传播疾病的潜在缓解策略。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。

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.