![]() ![]() The face-mask microstructure with the relatively larger pore, penetrating the main flow direction, shows a high quality factor. ![]() Six different face-mask domains are prepared, and the pressure drop and droplet collection efficiency are calculated for two different droplet diameters. To describe the complex geometry of the actual fibers, a wall boundary model is used, in which the immersed boundary method is used for the fluid phase, and the signed distance function is used to determine the contact between the droplet and fiber surface. Three-dimensional image analysis by x-ray computed tomography is used to obtain the microstructures of two types of commercial face masks, and the aerosol permeation behavior in the obtained microstructures is investigated with a numerical method coupled with computational fluid dynamics and a discrete phase model. Herein, we present a numerical simulation model to understand the collection behavior of aerosols containing submicron-sized droplets inside a realistic microstructure of commercially available face masks. These findings for the dynamic wettability of fibrous media will be useful in the fight against infectious droplets.įace masks act as air filters that collect droplets and aerosols, and they are widely used to prevent infectious diseases, such as COVID-19. Significantly, the resulting topographies of the microfibers managed the dynamic wettability of droplets at the multiscale, which reduced the probability of contamination with impact droplets and suppressed the wetting transition upon evaporation. To resolve this, we carved nanowalls on the pristine fibers by plasma etching, which effectively suppressed such wetting phenomena. Moreover, droplets easily adhered to the pristine layer during droplet impact tests and then yielding widespread areas of contamination on the microfibers. The contact angle (CA) values of small droplets on pristine fibrous media showed sudden decrements, especially on a single microfiber, owing to the lack of air cushions for the tiny droplets. Herein, we characterized the wettability of fibrous layers, which revealed that a multiscale landscape of droplets ranged from the millimeter to the micrometer scale. However, wetting behaviors at the single-microfiber level remain poorly understood. Unlike large droplets, microdroplets can interact sensitively with the fibers they contact with and are prone to evaporation. Meanwhile, millimeter-sized droplets are frequently used for wettability characterization, even with facial mask applications, although these applications have a droplet-size target range that spans from millimeters to aerosols measuring less than a few micrometers. Liquid mobility is ubiquitous in nature, with droplets emerging at all size scales, and artificial surfaces have been designed to mimic such mobility over the past few decades. This research highlights application of Euler-Lagrange model to represent the trajectory of cough droplets influenced by indoor condition with horizontal wind, in the effort to strengthen safety and health judgement in the event of a pandemic. ![]() Deposition at transmitter body is possible due to recirculation effect of incoming wind generated between transmitter and receiver, leading to 3.7 times higher deposited mass in lower RH as compared to in higher RH. Droplet particles settle on the floor within 1.50 s revealed 0.66 mg deposited mass in higher RH, while 0.26 mg of droplets deposited in lower RH. In a light wind breeze, droplet mass of 5.15 mg deposited on receiver body within 0.5 s of transmission when RH is 40%, while only 3.29 mg droplets reached receiver in RH of 99.5%. Surrounding air with higher RH leads to a larger mean diameter of particles due to hygroscopic growth effect, while evaporation effect dominates in lower air RH, leading to particle shrinkage. Simulation result revealed increasing wind velocity according to Beaufort wind scale of 1.0 to 3.9 m/s, increases transmission rate due to enhanced convection effect. The effect of different indoor parameters towards airborne transmission are investigated, which include wind velocity, air relative humidity (RH), and exposure time after emission. ANSYS Fluent 2022 R1 software is utilised in this research to numerically investigate and visualize flow pattern in a closed environment with cross ventilation and its effect to the emitted droplets deposition. This has motivated the present study to obtain the direct impact of flow field to the physical nature of transmission. Prediction of airborne transmission in different environmental condition remains as the research challenge in the field. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |