Numerical Study of the Transmission of Exhaled Droplets between the Instructor and Students in a Typical Classroom

Abstract

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 (SNAC) and the exceedance in exposure ratio (EER), were introduced to examine the effect of the said parameters on student exposure to the harmful droplets. The study revealed that the 5 mm droplets were less hazardous as they resulted in an 87% reduction in exposure when compared with the small 1 mm size droplets. We also found that when the ventilation rate ratio (VRR) 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 VRR 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 VRR equal to 2.

Structural and Environmental Safety Studies of the Holy Mosque Area Using CFD

“…The majority of the CFD outdoor wind models for different cases of the study, such as the current research, used K-ε turbulence models [62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]: whereas the majority of the researchers used the standard K-ε turbulence model [62][63][64][65][66][67][68][69][70][71][72][73], some [74][75][76] used RNG K-ε turbulence model and others [77][78][79][80][81] used the Renormalization k-ε turbulence model. On the other hand, some researchers used large eddy simulation (LES) turbulence models such as [82][83][84][85].…”

Role of Fluid Dynamics in Infectious Disease Transmission: Insights from COVID-19 and Other Pathogens

“…The fluid dynamics of exhaled multiphase turbulent puff clouds have significant implications for safety measures, physical/social distancing, respiratory protection of healthcare workers, and indoor air hygiene [89]. Public health policymakers are currently addressing these pressing issues owing to the lack of previous research investment in these areas [90].…”

CFD Simulations of Small Particle Behavior with Blower‐Driven Airflows in Single‐Family Residential Buildings

“…Compared to experimental methods, numerical modeling approaches are more convenient, time-saving, and cost-effective to investigate and visualize the transmission pathways of airborne respiratory droplets. Computational fluid dynamics (CFD), as the most popular numerical modeling tool, has been widely applied to model and investigate the dispersion of airborne particles and infectious agents in confined spaces, such as a hospital ward [22][23][24][25][26][27][28][29][30][31], a hospital isolation room [32][33][34][35][36], a hospital clinic room [37], a hospital waiting room [38], a children's recovery room [38], an intensive care room [22,39], an operating room [40,41], a classroom [42][43][44][45][46][47][48][49][50][51][52][53], an office room [54][55][56][57], a conference room [58], a dining room [59], a restaurant [60,61], small flats in a high-rise residential building [62], an elevator cabin …”