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Chillón SA, Fernandez-Gamiz U, Zulueta E, Ugarte-Anero A, Blanco JM. Numerical performance of CO 2 accumulation and droplet dispersion from a cough inside a hospital lift under different ventilation strategies. Sci Rep 2024; 14:6843. [PMID: 38514758 PMCID: PMC10957917 DOI: 10.1038/s41598-024-57425-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 03/18/2024] [Indexed: 03/23/2024] Open
Abstract
The impact of mechanical ventilation on airborne diseases is not completely known. The recent pandemic of COVID-19 clearly showed that additional investigations are necessary. The use of computational tools is an advantage that needs to be included in the study of designing safe places. The current study focused on a hospital lift where two subjects were included: a healthy passenger and an infected one. The elevator was modelled with a fan placed on the middle of the ceiling and racks for supplying air at the bottom of the lateral wall. Three ventilation strategies were evaluated: a without ventilation case, an upwards-blowing exhausting fan case and a downwards-blowing fan case. Five seconds after the elevator journey began, the infected person coughed. For the risk assessment, the CO2 concentration, droplet removal performance and dispersion were examined and compared among the three cases. The results revealed some discrepancies in the selection of an optimal ventilation strategy. Depending on the evaluated parameter, downward-ventilation fan or no ventilation strategy could be the most appropriate approach.
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Affiliation(s)
- Sergio A Chillón
- Energy Engineering Department, School of Engineering of Vitoria-Gasteiz, University of the Basque Country, UPV/EHU, Nieves Cano 12, 01006, Vitoria-Gasteiz, Araba, Spain
| | - Unai Fernandez-Gamiz
- Energy Engineering Department, School of Engineering of Vitoria-Gasteiz, University of the Basque Country, UPV/EHU, Nieves Cano 12, 01006, Vitoria-Gasteiz, Araba, Spain.
| | - Ekaitz Zulueta
- Automatic and Simulation Department, University of the Basque Country, UPV/EHU, Nieves Cano 12, 01006, Vitoria-Gasteiz, Araba, Spain
| | - Ainara Ugarte-Anero
- Energy Engineering Department, School of Engineering of Vitoria-Gasteiz, University of the Basque Country, UPV/EHU, Nieves Cano 12, 01006, Vitoria-Gasteiz, Araba, Spain
| | - Jesus Maria Blanco
- Energy Engineering Department, School of Engineering, University of the Basque Country (UPV/EHU), Plaza Ingeniero Torres Quevedo, Building 1, 48013, Bilbao, Spain
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Kumar S, Klassen M, Klassen D, Hardin R, King MD. Dispersion of sneeze droplets in a meat facility indoor environment - Without partitions. ENVIRONMENTAL RESEARCH 2023; 236:116603. [PMID: 37454802 DOI: 10.1016/j.envres.2023.116603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/26/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
Spreading patterns of the coronavirus disease (COVID-19) showed that infected and asymptotic carriers both played critical role in escalating transmission of virus leading to global pandemic. Indoor environments of restaurants, classrooms, hospitals, offices, large assemblies, and industrial installations are susceptible to virus outbreak. Industrial facilities such as fabrication rooms of meat processing plants, which are laden with moisture and fat in indoor air are the most sensitive spaces. Fabrication room workers standing next to each other are exposed to the risk of long-range viral droplets transmission within the facility. An asymptomatic carrier may transmit the virus unintentionally to fellow workers through sporadic sneezing leading to community spread. A novel Computational Fluid Dynamics (CFD) model of a fabrication room with typical interior (stationary objects) was prepared and investigated. Study was conducted to identify indoor airflow patterns, droplets spreading patterns, leading droplets removal mechanism, locations causing maximum spread of droplets, and infection index for workers along with stationary objects in reference to seven sneeze locations covering the entire room. The role of condensers, exhaust fans and leakage of indoor air through large and small openings to other rooms was investigated. This comprehensive study presents flow scenarios in the facility and helps identify locations that are potentially at lower or higher risk for exposure to COVID-19. The results presented in this study are suitable for future engineering analyses aimed at redesigning public spaces and common areas to minimize the spread of aerosols and droplets that may contain pathogens.
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Affiliation(s)
- Sunil Kumar
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA.
| | | | - David Klassen
- Department of Mechanical Engineering, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Robert Hardin
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Maria D King
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA.
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Ugarte-Anero A, Fernandez-Gamiz U, Portal-Porras K, Lopez-Guede JM, Sanchez-Merino G. Numerical study of different ventilation schemes in a classroom for efficient aerosol control. Heliyon 2023; 9:e19961. [PMID: 37809677 PMCID: PMC10559565 DOI: 10.1016/j.heliyon.2023.e19961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 07/11/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023] Open
Abstract
The air quality is a parameter to be controlled in order to live in a comfortable place. This paper analyzes the trajectory of aerosols exhaled into the environment in a classroom. Three scenarios are investigated; without ventilation, with natural and with mechanical ventilation. A multi-phase computational fluid study based on Eulerian-Lagrangian techniques is defined. Temperature and ambient relative humidity, as well as air velocity, direction and pressure is taken into account. For droplets evaporation, mass transfer and turbulent dispersion have been added. This work tends to be of great help in various areas, such as the field of medicine and energy engineering, aiming to show the path of aerosols dispersed in the air. The results show that the classroom with a mechanical ventilation scheme offers good results when it comes to an efficient control of aerosols. In all three cases, aerosols exhaled into the environment impregnate the front row student in the first 0.5 s. Reaching the time of 4, 2 and 1 s, in the class without ventilation, mechanical and natural ventilation, respectively, the aerosols have been already deposited on the table of the person in the first row, being exposed for longer in the case of no ventilation. Particles with a diameter of less than 20 μm are distributed throughout the classroom over a long period. The air jet injected into the interior space offers a practically constant relative humidity and a drop in temperature, slowing down the process of evaporation of the particles. In the first second, it can be seen that a mass of 0.0025 mg formed by 9 million droplets accumulates, in cases without ventilation and natural ventilation. The room with a mechanical installation accumulated 5.5 million particles of mass 0.0028 mg in the first second. The energy losses generated by natural ventilation are high compared to the other scenarios, exactly forty and twenty times more in the scenario with mechanical ventilation and without ventilation, respectively.
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Affiliation(s)
- Ainara Ugarte-Anero
- Nuclear Engineering and Fluid Mechanics Department, University of the Basque Country, UPV/EHU, Nieves Cano 12, Vitoria-Gasteiz, 01006, Araba, Spain
- Bioaraba, New Technologies and Information Systems in Health Research Group, Vitoria-Gasteiz, Spain
- Osakidetza Basque Health Service, Araba University Hospital, Medical Physics Department, Vitoria-Gasteiz, Spain
| | - Unai Fernandez-Gamiz
- Nuclear Engineering and Fluid Mechanics Department, University of the Basque Country, UPV/EHU, Nieves Cano 12, Vitoria-Gasteiz, 01006, Araba, Spain
- Bioaraba, New Technologies and Information Systems in Health Research Group, Vitoria-Gasteiz, Spain
- Osakidetza Basque Health Service, Araba University Hospital, Medical Physics Department, Vitoria-Gasteiz, Spain
| | - Koldo Portal-Porras
- Nuclear Engineering and Fluid Mechanics Department, University of the Basque Country, UPV/EHU, Nieves Cano 12, Vitoria-Gasteiz, 01006, Araba, Spain
| | - Jose Manuel Lopez-Guede
- Bioaraba, New Technologies and Information Systems in Health Research Group, Vitoria-Gasteiz, Spain
- Osakidetza Basque Health Service, Araba University Hospital, Medical Physics Department, Vitoria-Gasteiz, Spain
- System Engineering and Automation Control Department, University of the Basque Country, UPV/EHU, Nieves Cano 12, Vitoria-Gasteiz, 01006, Araba, Spain
| | - Gaspar Sanchez-Merino
- Bioaraba, New Technologies and Information Systems in Health Research Group, Vitoria-Gasteiz, Spain
- Osakidetza Basque Health Service, Araba University Hospital, Medical Physics Department, Vitoria-Gasteiz, Spain
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Bahramian A, Mohammadi M, Ahmadi G. Effect of indoor temperature on the velocity fields and airborne transmission of sneeze droplets: An experimental study and transient CFD modeling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159444. [PMID: 36252673 PMCID: PMC9569930 DOI: 10.1016/j.scitotenv.2022.159444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/08/2022] [Accepted: 10/11/2022] [Indexed: 05/03/2023]
Abstract
The spread of the COVID-19 pandemic through the airborne transmission of coronavirus-containing droplets emitted during coughing, sneezing, and speaking has now been well recognized. This study presented the effect of indoor temperature (T∞) on the airflow dynamics, velocity fields, size distribution, and airborne transmission of sneeze droplets in a confined space through experimental investigation and computational fluid dynamic (CFD) modeling. The CFD simulations were performed using the renormalization group k-ε turbulence model. The experimental shadowgraph imaging and CFD simulations showed the time evolution of sneeze droplet concentrations into the turbulent expanded puff, droplet cloud, and fully-dispersed droplets. Also, the predicted mean velocity of droplets was compared with the obtained experimental data to assess the accuracy of the results. In addition, the validated computational model was used to study the sneeze complex airflow behavior and airborne transmission of small, medium, and large respiratory droplets in confined spaces at different temperatures. The warm room showed more than ∼14 % increase in airborne aerosols than the room with a mild temperature. The study provides information on the effect of room temperature on the evaporation of respiratory droplets during sneezing. The findings of this fundamental study may be used in developing exposure guidelines by controlling the temperature level in indoor environments to reduce the exposure risk of COVID-19.
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Affiliation(s)
- Alireza Bahramian
- Department of Chemical Engineering, Hamedan University of Technology, P.O. Box 65155, Hamedan, Iran.
| | - Maryam Mohammadi
- Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Goodarz Ahmadi
- Department of Mechanical and Aerospace Engineering, Clarkson University, Potsdam, NY 13699, USA
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Nie W, Liu F, Xu C, Peng H, Zhang H, Mwabaima FI. Study on the optimal parameter range of droplet-wrapped respirable dust in spray dustfall by mesoscopic method. ENVIRONMENTAL RESEARCH 2022; 214:114035. [PMID: 35932835 DOI: 10.1016/j.envres.2022.114035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/23/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
Coal miners on the fringes of cities are often exposed to respirable dust hazards. Spray is one of the most effective dust reduction measures. When studying the coupling and collision behavior of droplets and dust particles, it is helpful to optimize the parameter range of the droplets to capture dust particles at the mesoscopic level, to determine the effect of the spray field on the dust particles at the macroscopic level. In this study, the volume of fluid (VOF) method was used to track the interface of multiphase flow. A numerical simulation of 13 working conditions was carried out using the control variable method. Based on the numerical simulation results, we obtained the optimal parameter range for dust to be encapsulated by droplets. To confirm the reliability of the simulation, we independently developed an experimental system and conducted experiments. The simulation results obtained were measured using the experimental system, and an optimal droplet parameter range of 7 μm to settle dust in a coal mining face was determined. Numerical simulation using a mesoscopic method to study dust-spray coupling produced reliable results, which can be used in the practical application of spray dust reduction and has wider relevance for practical engineering.
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Affiliation(s)
- Wen Nie
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Fei Liu
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Changwei Xu
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Huitian Peng
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Hao Zhang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
| | - Felicie Ilele Mwabaima
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao, 266590, China; State Key Laboratory of Mining Disaster Prevention and Control Co-found by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao, 266590, China.
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Oh W, Ooka R, Kikumoto H, Han M. Numerical modeling of sneeze airflow and its validation with an experimental dataset. INDOOR AIR 2022; 32:e13171. [PMID: 36437664 DOI: 10.1111/ina.13171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
In this study, we aimed at providing datasets using experimental results to validate the sneeze airflow. In addition, the boundary conditions for the sneeze simulation that could reproduce the sneeze airflow in the experimental results are presented and reviewed. The validation datasets were created by performing ensemble-average analysis with the experimental results of particle image velocimetry, and these were used to explore the boundary conditions to reproduce the sneeze airflow. As a result of the sneeze airflow reproduced by computational fluid dynamics simulation, the magnitude ranges of maximum velocity at the interface were observed to be 21.1-23.9 m/s for males and 17.9-20.3 m/s for females, which were higher than those of coughing. Compared with the experimental results, the root-mean-square error range for the overall airflow distribution was 0.19-0.23 m/s, whereas the error range for the magnitude of the maximum velocity at a criterion point was 0.03-0.08 m/s. The total sneezing airflow volume was in the range of 0.36-0.48 L, which was relatively low compared with that of coughing. Thus, this study provides important fundamental boundary conditions for computational fluid dynamics analysis, validated by experimental results, to interpret the spread of infectious particles by sneezing.
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Affiliation(s)
- Wonseok Oh
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Ryozo Ooka
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Hideki Kikumoto
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Mengtao Han
- School of Architecture and Urban Planning, Huazhong University of Science and Technology, Wuhan, China
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