Validation, verification, and quality control of computational fluid dynamics analysis for indoor environments using a computer‐simulated person with respiratory tract

Yoo, Sung‐Jun; Ito, Kazuhide

doi:10.1002/2475-8876.12301

Cited by 24 publications

(4 citation statements)

References 66 publications

(105 reference statements)

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“…The geometry used in this study consisted of two male human bodies [24], standing face-toface and separated by a 1 m distance in an 8×8×8 m 3 domain. The two virtual manikins complied with the guidelines proposed by Yoo and Ito [25]. "Human 1" had a simplified circular mouth geometry for a loud speaking setting, while "Human 2" was integrated with a respiratory tract for continuous breathing, provided and previously validated by Phuong and Ito [26], as presented in Fig 1 . This respiratory tract was further simplified by removing the oral cavity to minimize cell number, starting from the nasal vestibule until the 7 th generation of bronchial tubes (4 th bifurcation).…”

Section: Domain Designmentioning

confidence: 99%

Large eddy simulation of droplet transport and deposition in the human respiratory tract to evaluate inhalation risk

Murga

Bale

et al. 2023

PLoS Comput Biol

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As evidenced by the worldwide pandemic, respiratory infectious diseases and their airborne transmission must be studied to safeguard public health. This study focuses on the emission and transport of speech-generated droplets, which can pose risk of infection depending on the loudness of the speech, its duration and the initial angle of exhalation. We have numerically investigated the transport of these droplets into the human respiratory tract by way of a natural breathing cycle in order to predict the infection probability of three strains of SARS-CoV-2 on a person who is listening at a one-meter distance. Numerical methods were used to set the boundary conditions of the speaking and breathing models and large eddy simulation (LES) was used for the unsteady simulation of approximately 10 breathing cycles. Four different mouth angles when speaking were contrasted to evaluate real conditions of human communication and the possibility of infection. Breathed virions were counted using two different approaches: the breathing zone of influence and direction deposition on the tissue. Our results show that infection probability drastically changes based on the mouth angle and the breathing zone of influence overpredicts the inhalation risk in all cases. We conclude that to portray real conditions, the probability of infection should be based on direct tissue deposition results to avoid overprediction and that several mouth angles must be considered in future analyses.

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Section: Domain Designmentioning

confidence: 99%

Large eddy simulation of droplet transport and deposition in the human respiratory tract to evaluate inhalation risk

Murga

Bale

et al. 2023

PLoS Comput Biol

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“…For the wall treatment of particles, trap boundary conditions were applied for all wall surfaces in bus cabins including CSP, and escape boundary conditions were set for all mouth openings and exhaust outlets in bus cabins. For precise prediction of the microclimate around CSPs, grid independence was carefully checked based on the suggested methodology in previous studies [9,[33][34][35][36][37][38][39][40]. Six grid designs around CSPs were prepared with variations in grid resolution, and grid independence was carefully tested based on the analysis results of the coefficient of variation of the root mean square error (CV (RMSE)) and coefficient of determination (R 2 ) [41].…”

Section: Analytical and Boundary Conditionsmentioning

confidence: 99%

Computational Fluid and Particle Dynamics Analyses for Prediction of Airborne Infection/Spread Risks in Highway Buses: A Parametric Study

Yoo,

Yamauchi,

Park

et al. 2023

Fluids

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Highway buses are used in a wide range of commuting services and in the tourist industry. The demand for highway bus transportation has dramatically increased in the recent post-pandemic world, and airborne transmission risks may increase alongside the demand for highway buses, owing to a higher passenger density in bus cabins. We developed a numerical prediction method for the spatial distribution of airborne transmission risks inside bus cabins. For a computational fluid dynamics analyses, targeting two types of bus cabins, sophisticated geometries of bus cabins with realistic heating, ventilation, and air-conditioning were reproduced. The passengers in bus cabins were reproduced using computer-simulated persons. Airflow, heat, and moisture transfer analysis were conducted based on computational fluid dynamics, to predict the microclimate around passengers and the interaction between the cabin climate and passengers. Finally, droplet dispersion analysis using the Eulerian–Lagrangian method and an investigation of the spatial distribution of infection/spread risks, assuming SARS-CoV-2 infection, were performed. Through parametric analyses of passive and individual countermeasures to reduce airborne infection risks, the effectiveness of countermeasures for airborne infection was discussed. Partition installation as a passive countermeasure had an impact on the human microclimate, which decreased infection risks. The individual countermeasure, mask-wearing, almost completely prevented airborne infection.

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“…The realistic trachea-bronchus model was created from CT scans, and details on the process are available in the previous study by Ito (Ito, 2016). This trachea-bronchus model, in combination with the nasal cavity, has been validated by our research group, providing reliable results in diverse research themes (C. Yoo & Ito, 2022;Kuga et al, 2021Kuga et al, , 2022Kuga et al, , 2023Murga et al, 2023;Khoa, Li, et al, 2023).…”

Section: A Numerical Model Geometrymentioning

confidence: 99%

Coupled Eulerian Wall Film–Discrete Phase model for predicting respiratory droplet generation during a coughing event

Khoa,

Kuga,

Inthavong

et al. 2023

Physics of Fluids

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Infectious respiratory diseases have long been a serious public health issue, with airborne transmission via close person-to-person contact being the main infection route. Coughing episodes are an eruptive source of virus-laden droplets that increase the infection risk of susceptible individuals. In this study, the droplet generation process during a coughing event was reproduced using the Eulerian wall film (EWF) model, and the absorption/expulsion of droplets was tracked using the discrete phase model (DPM). A realistic numerical model that included the oral cavity with teeth features and the respiratory system from the throat to the first bifurcation was developed. A coughing flow profile simulated the flow patterns of a single coughing episode. The EWF and DPM models were coupled to predict the droplet formation, generation, absorption, and exhalation processes. The results showed that a large droplet number concentration was generated at the beginning of the coughing event, with the peak concentration coinciding with the peak cough rate. Analysis of the droplet site of origin showed that large amounts of droplets were generated in the oral cavity and teeth surface, followed by the caudal region of the respiratory system. The size of the expelled droplets was 0.25–24 μm, with the peak concentration at 4–8 μm. This study significantly contributes to the realm on the site of origin and localized number concentration of droplets after a coughing episode. It can facilitate studies on infection risk assessment, droplet dispersion, and droplet generation mechanisms from other sneezing or phonation activities.

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Validation, verification, and quality control of computational fluid dynamics analysis for indoor environments using a computer‐simulated person with respiratory tract

Cited by 24 publications

References 66 publications

Large eddy simulation of droplet transport and deposition in the human respiratory tract to evaluate inhalation risk

Large eddy simulation of droplet transport and deposition in the human respiratory tract to evaluate inhalation risk

Computational Fluid and Particle Dynamics Analyses for Prediction of Airborne Infection/Spread Risks in Highway Buses: A Parametric Study

Coupled Eulerian Wall Film–Discrete Phase model for predicting respiratory droplet generation during a coughing event

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