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Noninvasive aerosol removal processes are sought after in manufacturing industries that utilize powder product recovery. Traditionally, cyclone separators are commonly deployed, however, this method is energy intensive; space demanding and inefficient for particles with a diameter less than 5 μm. While acoustically induced aerosols depositions was proposed as an alternative aerosol removal method which addressed such limitations, the underlying parameters determining the performance of such technique are yet to be explored. This study examines those underlying parameters determining the efficiency of acoustic aerosol removal, such as; the removal efficiencies, varying aerosol inputs, particle initial concentrations and size distributions. Experimental results showed that given the same initial particle number concentrations, aerosols containing two particles sizes, larger (seed) and smaller (test) particles, improved the removal efficiencies for the test particles. A higher seed to test particle concentration ratio further enhanced this effect. For particle number concentrations ranging above 2.0×10 4 #/cm 3 , the increase in concentrations enhanced the removal efficiency of aerosols. Further analysis conducted by numerical simulations demonstrated that the deposition of particles depended on their sizes and their initial positions in the acoustic field. A new parameter, deposition cell ratio was proposed to quantify the deposition probability for particles at a given size and in a given domain. Results suggested that the deposition probability of a group of aerosols may be a function of the sum of the probabilities of each individual particle. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic, WHO and CDC suggest people stay 1 m and 1.8 m away from others, respectively. Keeping social distance can avoid close contact and mitigate infection spread. Many researchers suspect that suggested distances are not enough because aerosols can spread up to 7–8 m away. Despite the debate on social distance, these social distances rely on unobstructed respiratory activities such as coughing and sneezing. Differently, in this work, we focused on the most common but less studied aerosol spread from an obstructed cough. The flow dynamics of a cough jet blocked by the backrest and gasper jet in a cabin environment was characterized by the particle image velocimetry (PIV) technique. It was proved that the backrest and the gasper jet can prevent the front passenger from droplet spray in public transportation where maintaining social distance was difficult. A model was developed to describe the cough jet trajectory due to the gasper jet, which matched well with PIV results. It was found that buoyancy and inside droplets almost do not affect the short-range cough jet trajectory. Infection control measures were suggested for public transportation, including using backrest/gasper jet, installing localized exhaust, and surface cleaning of the backrest. • Keeping social distance in public transportation is difficult, meaning high risk. • Flow dynamics of cough jet in a cabin environment is studied by PIV technique. • Backrest and gasper jet can be compensation for not keeping social distance. • Localized exhaust under each seat is suggested to timely remove bulk aerosols. • A universal model is proposed to predict the obstructed cough jet trajectory. [ABSTRACT FROM AUTHOR]

Understanding of the droplet detachment behavior from rough hydrophilic surfaces is important in many biological and industrial applications such as biomedicine, surface coating, and pathogen-laden aerosol resuspension. Due to the partial detachment of the droplet on hydrophilic surfaces, leaving behind some droplet residues, the adhesion behavior is extremely complicated. Here we reveal a new adhesion mechanism between a droplet and a rough hydrophilic surface. The adhesion behavior is controlled by a liquid film stuck in the surface microstructure. We establish a model to describe the contributions of liquid film and naked solid peaks, to the work of adhesion and verify the model experimentally. We also find that the normal adhesion force is about 3.35 ± 0.25 times of the lateral adhesion force for different surface roughness, meaning that the separation direction is an important factor affecting adhesion due to the different separation mechanisms. The results of this work shed new insights on the understanding of droplet detachment and adhesion to a rough surface. • Rough surface attaches larger liquid aerosol than smooth surface, while rough surface holds smaller solid aerosol. • A model is proposed and experimentally verified to reveal adhesion mechanism of a liquid aerosol to a rough surface. • Normal adhesion force is about 3.35±0.25 times of lateral adhesion force, which is independent of surface roughness. [ABSTRACT FROM AUTHOR]