The COVID-19 pandemic has revealed critical knowledge gaps in our understanding of and a need to update the traditional view of transmission pathways for respiratory viruses. The long-standing definitions of droplet and airborne transmission do not account for the mechanisms by which virus-laden respiratory droplets and aerosols travel through the air and lead to infection. In this Review, we discuss current evidence regarding the transmission of respiratory viruses by aerosols-how they are generated, transported, and deposited, as well as the factors affecting the relative contributions of droplet-spray deposition versus aerosol inhalation as modes of transmission. Improved understanding of aerosol transmission brought about by studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requires a reevaluation of the major transmission pathways for other respiratory viruses, which will allow better-informed controls to reduce airborne transmission.

Airborne transmission of respiratory viruses.

https://pure.tue.nl/ws/files/67843762/1_s2.0_S0306261917303744_main.pdf

Effect of pitch angle on power performance and aerodynamics of a vertical axis wind turbine

A review on computational fluid dynamic simulation techniques for Darrieus vertical axis wind turbines

Characterization of aerodynamic performance of vertical axis wind turbines : impact of operational parameters

https://cyberleninka.org/article/n/84858.pdf

Leading-edge serrations for performance improvement on a vertical-axis wind turbine at low tip-speed-ratios

Power output analysis and optimization of two straight-bladed vertical-axis wind turbines

Public health reports indicate that high PM2.5 concentration can impair the respiratory health of the residents, especially for those affected by asthma. Therefore, there is a need to determine the deposition mechanism and efficiencies for PM2.5 in asthmatic human airways. In this study, gas flow dynamics and deposition fractions (DFs) of PM2.5 in generations 10–11 of Weibel's lung model were investigated where the two-phase gas-solid flow behaviors in healthy and asthmatic airways were considered. The gas phase was modeled as a transient laminar and incompressible flow while the discrete phase model (DPM) was applied for the particle phase. Three different air flow rates under rest, light activity, and moderate exercise were considered. For the healthy airways, higher total mass DFs were observed during a moderate exercise as compared to rest and light activity conditions. Deposition fractions were higher in asthmatic airways compared to those of healthy ones, stemming from tapering in the airways as well as complex secondary flow fields, namely, Dean vortices, in the folds. Deposition was mainly due to inertial forces of particles, but a small amount of PM2.5 was deposited near the entrance of asthmatic tube, as a result of the secondary flow. The numerical results revealed that the Dean vortices was an important factor for particle deposition. With increased DF, asthmatic people have a higher total respiratory dose of PM2.5 for a given exposure compared to healthy individuals. Thus contributing to their increased susceptibility to adverse health effects caused by PM2.5.

/pdf/flow-dynamics-and-pm2-5-deposition-in-healthy-and-asthmatic-txwu1z47fg.pdf

Chii Jong Hwang

Papers

Power output analysis and optimization of two straight-bladed vertical-axis wind turbines

Flow dynamics and PM2.5 deposition in healthy and asthmatic airways at different inhalation statuses

An investigation for airflow and deposition of PM 2.5 contaminated with SAR-CoV-2 virus in healthy and diseased human airway.