scholarly journals Numerical Investigation of Bioaerosol Transport in a Compact Lavatory

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 526
Author(s):  
Jingyuan Wan ◽  
Jianjian Wei ◽  
Yingtien Lin ◽  
Tengfei (Tim) Zhang
Keyword(s):  
Large Fraction ◽  
Aerosol Deposition ◽  
Control Measures ◽  
Thermal Manikin ◽  
Thermal Plume ◽  
User Behaviors ◽  
Toilet Seat ◽  
Computational Fluid Dynamics Cfd ◽  
Respiratory Droplets ◽  
Fertile Area

The lavatory is a fertile area for the transmission of infectious disease through bioaerosols between its users. In this study, we built a generic compact lavatory model with a vacuum toilet, and computational fluid dynamics (CFD) is used to evaluate the effects of ventilation and user behaviors on the airflow patterns, and the resulting fates of bioaerosols. Fecal aerosols are readily released into the lavatory during toilet flush. Their concentration rapidly decays in the first 20 s after flushing by deposition or dilution. It takes about 315 s to 348 s for fine bioaerosols (<10 µm in diameter) to decrease to 5% of the initial concentration, while it takes 50 and 100 µm bioaerosols approximately 11 and <1 s, respectively, to completely deposit. The most contaminated surfaces by aerosol deposition include the toilet seat, the bowl, and the nearby walls. The 10 µm aerosols tend to deposit on horizontal surfaces, while the 50 and 100 µm bioaerosols almost always deposit on the bowl. In the presence of a standing thermal manikin, the rising thermal plume alters the flow field and more bioaerosols are carried out from the toilet; a large fraction of aerosols deposit on the manikin’s legs. The respiratory droplets generated by a seated coughing manikin tend to deposit on the floor, legs, and feet of the manikin. In summary, this study reveals the bioaerosol dilution time and the easily contaminated surfaces in a compact lavatory, which will aid the development of control measures against infectious diseases.

scholarly journals Laminar flow ventilation system to prevent airborne infection during exercise in the COVID-19 crisis: A single-center observational study

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0257549
Author(s):  
Yoshinori Katsumata ◽  
Motoaki Sano ◽  
Hiroki Okawara ◽  
Tomonori Sawada ◽  
Daisuke Nakashima ◽  
...  
Keyword(s):  
Observational Study ◽  
Exercise Intensity ◽  
Healthy Subjects ◽  
Ventilation System ◽  
Control Measures ◽  
Anaerobic Exercise ◽  
Single Center ◽  
Exercise Tests ◽  
Respiratory Droplets ◽  
Single Center Observational Study

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 μm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p<0.001). The amount of respiratory droplets significantly increased after LT. The LFVS enabled a significant decrease in respiratory droplets during anaerobic exercise in healthy subjects. This study’s findings will aid in exercising safely during this pandemic.

Study on a Flutter Stability Control Measure of Fabricated Steel Truss Bridge

2014 ◽  
Vol 620 ◽  
pp. 7-13
Author(s):  
Cheng Long Zhang ◽  
Qiang Wang ◽  
Xiao Hui He ◽  
En Jiang Bian ◽  
Jie He
Keyword(s):  
Control Measure ◽  
Stability Control ◽  
Control Measures ◽  
Two Dimensional ◽  
Flutter Speed ◽  
Steel Truss Bridge ◽  
Steel Truss ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamics Cfd ◽  
Truss Bridge

Abstract. To improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting tuyere is put forward. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), with the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of tuyere is simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of origin and tuyere models are obtained. Through analysis, for the certain type fabricated steel truss bridge, the tuyere can improve its flutter stability. It illustrates the feasibility and reliability, and lays the foundation for further applied in practical projects.

Uptake of Soluble Gases in the Entire Respiratory Systems of Rats and Humans Using Transient CFD/PBPK Models

2013 ◽  
Author(s):  
S. Kabilan ◽  
A. Kuprat ◽  
D. Einstein ◽  
J. Carson ◽  
R. Jacob ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Hydrogen Sulfide ◽  
Three Dimensional ◽  
Aerosol Deposition ◽  
Water Soluble ◽  
Computational Techniques ◽  
Nasal Airways ◽  
Cfd Models ◽  
Pbpk Models ◽  
Computational Fluid Dynamics Cfd

With the advancement of experimental and computational techniques, three-dimensional (3D) computational fluid dynamics (CFD) airflow models of the respiratory system have increasingly been used to evaluate aerosol deposition, gas exchange and airflow characteristics under various physiological and/or disease conditions. One specific application that is emerging in the field of toxicology is assessing the risk for exposure to highly reactive, water-soluble gases and vapors including formaldehyde, acetaldehyde, hydrogen sulfide, and acrolein by coupling CFD models of nasal airways of rats and humans to physiological based pharmacokinetic (PBPK) models.

scholarly journals Knowledge and awareness about airborne pathogens and its prevention among the general public

2020 ◽  
Vol 11 (SPL3) ◽  
pp. 279-286
Author(s):  
Ashritha M ◽  
Geetha R V ◽  
Jayalakshmi Somasundaram
Keyword(s):  
General Public ◽  
Health Workers ◽  
Control Measures ◽  
Dust Particles ◽  
Protective Measures ◽  
The People ◽  
Airborne Disease ◽  
Protection And Control ◽  
And Control ◽  
Respiratory Droplets

The airborne disease is mainly caused by the pathogens, which spread through respiratory droplets while coughing, sneezing or talking. Infection protection and control measures are taken to prevent the possible spread of , which also spreads through respiratory droplets. Discharged microbes are suspended in the air as dust particles and even in the form of droplets. The Middle East respiratory syndrome is caused by wherein the health workers are at a higher risk. Hence, awareness must be created in order to reduce a number of cases. The preventive measures are mainly taken in health care as patients are susceptible to diseases. It is essential for all the people to become aware and take steps according. The survey was distributed online to around 100 participants of various places of Tamil regarding the awareness of airborne pathogens. From this above study, it could be noticed that around 85% of the people are aware of the airborne pathogen whereas 15% of the people are not aware of. 64% of people have a good knowledge of the symptoms of any type of airborne disease. the protective measures that must be taken, about 65% of the people are conscious of doing it. The study concludes that there is awareness of airborne pathogens and its prevention among the general public.

RESEARCH ON A FLUTTER STABILITY CONTROL MEASURE OF A FABRICATED STEEL TRUSS BRIDGE

2017 ◽  
Vol 41 (2) ◽  
pp. 181-195
Author(s):  
He Xiaohui ◽  
Wang Qiang ◽  
Zhang Chenglong ◽  
Zhang Shunfeng ◽  
Gao Yaming
Keyword(s):  
Control Measure ◽  
Stability Control ◽  
Control Measures ◽  
Two Dimensional ◽  
Flutter Speed ◽  
Steel Truss Bridge ◽  
Steel Truss ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamics Cfd ◽  
Truss Bridge

In order to improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting guiding plates is proposed. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), and by use of the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of setting guiding plates are simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of original and guiding-plated models are obtained. It is found that for a certain type fabricated steel truss bridge, the guiding plates can improve its flutter stability. Thus, the feasibility and reliability of setting the guiding plates are proved, and the foundation for its further application in practical projects is laid.

Numerical Analysis of Microclimate of Desk Displacement Ventilation Using a Zero-equation Turbulence Model

2004 ◽  
Vol 47 (2) ◽  
pp. 1-14 ◽  
Author(s):  
Bin Zhao ◽  
Zhao Zhang ◽  
Xudong Yang ◽  
Xianting Li ◽  
Dongtao Huang
Keyword(s):  
Turbulence Model ◽  
Indoor Environment ◽  
Measured Data ◽  
Thermal Plume ◽  
Environment Design ◽  
Cfd Model ◽  
Displacement Ventilation ◽  
Plume Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Pollutant Concentration Distribution

A computational fluid dynamics (CFD) program based on a zero-equation turbulence model is used to simulate the microclimate in a model office ventilated by desk displacement ventilation (DDV). DDV is a new ventilation concept that intends to combine the positive features of displacement ventilation and local task ventilation. The CFD model correctly predicts both the thermal plume and temperature stratification, and the calculated air temperature distributions agree with the measured data. The pollutant concentration distribution is further simulated to evaluate the microclimate of DDV. Results show that despite rather large discrepancies between simulated velocity distributions and experimental data, the zero-equation turbulence model may simulate the main characteristics (thermal plume, temperature, and qualitative velocity tendency) of DDV more quickly than other commonly used models, for instance, the k-ε model, and thus may be applied to similar cases in indoor environment design.

scholarly journals A nationwide study on the knowledge, awareness, and practices towards COVID-19 in Saudi Arabia

2021 ◽  
Vol 20 (1) ◽  
pp. 161-167
Author(s):  
Yaser M. Alahmadi ◽  
Sultan S. Al Thagfan
Keyword(s):  
Saudi Arabia ◽  
Clinical Symptoms ◽  
Face Mask ◽  
Control Measures ◽  
Chi Square ◽  
Cross Sectional ◽  
Attitudes And Practices ◽  
Chi Square Test ◽  
Respiratory Droplets ◽  
Self Administered Questionnaire

Purpose: To investigate public knowledge, awareness and practice regarding COVID-19 in Saudi Arabia.Methods: A cross-sectional descriptive study was conducted, with a 16-item self-administered questionnaire. Data was collected using social media as the platform a day after the lockdown commenced in Saudi Arabia and data collection lasted from March 25 to April 25, 2020. Chi-square test was performed to determine the association between the variables.Results: The results showed that 96 % (n = 1505) of adults were aware of the clinical symptoms of COVID-19 and 57.9 % (n = 908) correctly identified that a stuffy nose and sneezing were less common in persons infected with the virus. A majority (95.4 %, n = 1495) agreed that there was no established therapeutic treatment for COVID-19. Further, 91.7 % (n = 1437) agreed that the virus could spread via respiratory droplets and only 46.2 % (n = 724) acknowledged that wearing face mask helped prevent transmission. The results also showed that 83.2 % (n = 1299) of the participants thought that visiting crowded places increased the likelihood of transmission.Conclusion: The findings of this study reveal that adults in Saudi Arabia are cognizant of COVID-19 and maintained good attitudes and practices regarding it. Furthermore, health education programs aimed at improving awareness of the disease and appropriate control measures will be beneficial in curbing the virus pandemic. Keywords: Saudi Arabia, Coronavirus, Pandemic, COVID-19, Flu, Symptoms

Computational Fluid Dynamics Applicable to Cloth Design

2009 ◽  
Author(s):  
Ana M. F. Cunha ◽  
Jose´ C. F. Teixeira ◽  
Senhorinha F. C. F. Teixeira
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Human Body ◽  
Thermal Manikin ◽  
Clothing Insulation ◽  
Mass Transfer Processes ◽  
Different Temperatures ◽  
Computational Fluid Dynamics Cfd ◽  
Combined Simulation

Increasingly, different concepts such as safety, hygiene and comfort interact in the characterization of the workplaces. Being comfortable during periods of low activity, seems to be a requirement for most people and, secondly, in other sectors where performance is critical, the priorities are different. In both cases, the intellectual and physical performance is strongly affected by the sensation of thermal comfort. Thus, various approaches can be applied to provide comfort, for example, in the design of buildings and the selection of appropriate clothing. Comfortable clothing is a complex and interdisciplinary concept, consisting of a balance of the sensorial, psychological and physiological aspects [1, 2]. In objective terms, the behavior of the human body depends on several factors: temperature, air velocity and humidity, production of metabolic heat and clothing insulation. All these factors determine the heat and mass transfer processes between the human body and the environment. The Computational Fluid Dynamics (CFD) numerical simulation has been a powerful tool in this investigation field. A combined simulation of a room and a thermal manikin has been developed in the FLUENT code. Using a manikin with real dimensions, divided into parts with different temperatures, seems important to give accurate fluid flow and moisture distributions.

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