Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom
Conducting physical attendance exams during pandemics is a challenge facing many educational institutes and universities. Our study’s main objective is to numerically simulate the expected transmission of the harmful exhaled droplets of aerosols from an infected instructor to students in an exam roo...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-10-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/11/20/9767 |
| _version_ | 1797515394010841088 |
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| author | Mohamed Ismail Farouk Ahmed Fayez Nassar Mohamed Hassan Elgamal |
| author_facet | Mohamed Ismail Farouk Ahmed Fayez Nassar Mohamed Hassan Elgamal |
| author_sort | Mohamed Ismail Farouk |
| collection | DOAJ |
| description | Conducting physical attendance exams during pandemics is a challenge facing many educational institutes and universities. Our study’s main objective is to numerically simulate the expected transmission of the harmful exhaled droplets of aerosols from an infected instructor to students in an exam room ventilated by a number of spiral diffusers. Several critical parameters, including the droplet size, the ventilation rate, and status of the entrance door were considered in the analysis. Two dimensionless indices, i.e., the specific normalized average concentration (<i>SNAC</i>) and the exceedance in exposure ratio (<i>EER</i>), were introduced to examine the effect of the said parameters on student exposure to the harmful droplets. The study revealed that the 5 μm droplets were less hazardous as they resulted in an 87% reduction in exposure when compared with the small 1 μm size droplets. We also found that when the ventilation rate ratio (<i>VRR</i>) increased above unity, an upward entrainment process, due to the swirl diffuser, of the aerosol droplets took place, and consequently the risk of student exposure was reduced. The results also demonstrated that increasing <i>VRR</i> from zero to 1 and then to 2 decreased the exceedance in the student exposure from 3.5 to 2.15 and then to less than zero, respectively. The study also showed that keeping the lecture room’s main door open is recommended as this reduced the risk of exposure by 26% in the case of a <i>VRR</i> equal to 2. |
| first_indexed | 2024-03-10T06:44:52Z |
| format | Article |
| id | doaj.art-f42f6d7e27334c008433665b09d840b7 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-10T06:44:52Z |
| publishDate | 2021-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-f42f6d7e27334c008433665b09d840b72023-11-22T17:24:04ZengMDPI AGApplied Sciences2076-34172021-10-011120976710.3390/app11209767Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical ClassroomMohamed Ismail Farouk0Ahmed Fayez Nassar1Mohamed Hassan Elgamal2Civil Engineering Department, College of Engineering, Imam Mohammad Ibn Saud Islamic University, Riyadh 13318, Saudi ArabiaChemical Engineering Department, Faculty of Engineering, Cairo University, Cairo 12613, EgyptCivil Engineering Department, College of Engineering, Imam Mohammad Ibn Saud Islamic University, Riyadh 13318, Saudi ArabiaConducting physical attendance exams during pandemics is a challenge facing many educational institutes and universities. Our study’s main objective is to numerically simulate the expected transmission of the harmful exhaled droplets of aerosols from an infected instructor to students in an exam room ventilated by a number of spiral diffusers. Several critical parameters, including the droplet size, the ventilation rate, and status of the entrance door were considered in the analysis. Two dimensionless indices, i.e., the specific normalized average concentration (<i>SNAC</i>) and the exceedance in exposure ratio (<i>EER</i>), were introduced to examine the effect of the said parameters on student exposure to the harmful droplets. The study revealed that the 5 μm droplets were less hazardous as they resulted in an 87% reduction in exposure when compared with the small 1 μm size droplets. We also found that when the ventilation rate ratio (<i>VRR</i>) increased above unity, an upward entrainment process, due to the swirl diffuser, of the aerosol droplets took place, and consequently the risk of student exposure was reduced. The results also demonstrated that increasing <i>VRR</i> from zero to 1 and then to 2 decreased the exceedance in the student exposure from 3.5 to 2.15 and then to less than zero, respectively. The study also showed that keeping the lecture room’s main door open is recommended as this reduced the risk of exposure by 26% in the case of a <i>VRR</i> equal to 2.https://www.mdpi.com/2076-3417/11/20/9767aerosolsCOVID-19aerodynamicsANSYS-FluentventilationDiscrete Phase Model (DPM) |
| spellingShingle | Mohamed Ismail Farouk Ahmed Fayez Nassar Mohamed Hassan Elgamal Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom Applied Sciences aerosols COVID-19 aerodynamics ANSYS-Fluent ventilation Discrete Phase Model (DPM) |
| title | Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom |
| title_full | Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom |
| title_fullStr | Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom |
| title_full_unstemmed | Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom |
| title_short | Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom |
| title_sort | numerical study of the transmission of exhaled droplets between the instructor and students in a typical classroom |
| topic | aerosols COVID-19 aerodynamics ANSYS-Fluent ventilation Discrete Phase Model (DPM) |
| url | https://www.mdpi.com/2076-3417/11/20/9767 |
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