6–14 Several experimental and computational studies are now beginning to emerge, seeking to fill this major knowledge gap and yield improved science-based physical distancing guidelines (see Refs. 5 There is now mounting evidence that such guidelines are based on outdated scientific studies carried out decades ago, 6 which, among others, have overlooked the physics of respiratory emissions, the range of droplet size distribution such emissions produce, the turbulent flow processes that transport respiratory droplets, and the potential effects of ambient wind conditions on such transport. 1–5 However, recommended social distancing guidelines vary considerably, with the WHO recommending at least 1 m while the CDC recommending at least 1.8 m of separation. The World Health Organization (WHO), the United States Centers for Disease Control (CDC), and other public health organizations are recommending social distancing and the use of facial coverings as two of the most important weapons to curb the spread of the pandemic. ![]() Under outdoor conditions with a unidirectional mild breeze, however, leakage flow through the mask can cause saliva particulates to be entrained into the energetic shear layers around the body and transported very fast at large distances by the turbulent flow, thus limiting the effectiveness of facial masks.Īs the coronavirus disease of 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is spreading around the globe, it causes devastating loss of life, threatens to topple national health care systems, and wreaks havoc on the global economy. Thus, in indoor environments, either medical or non-medical grade facial masks can successfully limit the spreading of saliva particulates to others. We show that during indoor coughing some saliva particulates could travel up to 0.48 m, 0.73 m, and 2.62 m for the cases with medical grade, non-medical grade, and without facial masks, respectively. Our simulations (a) are carried out under both a stagnant ambient flow (indoor) and a mild unidirectional breeze (outdoor), (b) incorporate the effect of human anatomy on the flow, (c) account for both medical and non-medical grade masks, and (d) consider a wide spectrum of particulate sizes, ranging from 10 µm to 300 µm. ![]() To expand the scientific underpinnings of such recommendations, we carry out high-fidelity computational fluid dynamics simulations of unprecedented resolution and realism to elucidate the underlying physics of saliva particulate transport during human cough with and without facial masks. Social distancing and face masks are widely recommended around the globe to protect others and prevent the spread of the virus through breathing, coughing, and sneezing. This book collects the recent studies that have applied the CFD technique in analyzing several representative processes covering mechanical engineering, chemical engineering, environmental engineering, and thermal engineering.The coronavirus disease outbreak of 2019 has been causing significant loss of life and unprecedented economic loss throughout the world. Therefore, computational fluid dynamics (CFD) has emerged and been widely applied in various fields. With the technique of finite difference methods or finite element methods, attaining numerical solutions from the partial differential equations of mass, momentum, and energy have become achievable. However, obtaining the analytical solution of these fluid property distributions is technically difficult or impossible. These properties, such as velocity, turbulence, temperature, pressure, and concentration, play important roles in mass transfer, heat transfer, reaction rate, and force analysis. Identifying the temporal and spatial distribution of fluid dynamic properties is essential in analyzing the processes related to flows. H.įluid flows are encountered in our daily life as well as in engineering industries. ![]() ![]() Fluid flows are encountered in our daily life as well as in engineering industries.
0 Comments
Leave a Reply. |