Impact of impinging jet ventilation on thermal comfort and aerosol transmission: A numerical investigation in a densely-occupied classroom with solar effect

Journal of Building Engineering, Год журнала: 2024, Номер 94, С. 109872 - 109872

Опубликована: Июнь 19, 2024

Язык: Английский

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Simulation of the transition of respiratory droplets to aerosol states: Implications for pathogen spread

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

Airborne viruses constitute a real threat to the world and will continue do so in foreseeable future. Despite intensive research this field, physical mechanisms of droplet dynamics aerosols carrying these are far from being fully understood. Among many variables that have critical impact on dispersion virus droplets temperature relative humidity, as primarily determine longevity liquid phase droplets. While previous studied due different boundary conditions, we focus range below 10 μm shown be most likely pathway for airborne transmission. In study, spatial size evolution injected by mouth through coughing analyzed numerically compared combinations humidity. Of special interest would tracking aerosol part an indoor location serves volume conversation partner draw breath from. We present quantitative data dependence humidity plotted against time assisting quantifying possibility An Eulerian–Lagrangian approach is used study multiphase flow consisting continuous fluid formed air water vapor discrete water. analysis number aerosolized reaching depending It was concluded transmission partner, has largest influence

Язык: Английский

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Dispersion of expectorated cough droplets with seasonal influenza in an office

Physics of Fluids, Год журнала: 2023, Номер 35(8)

Опубликована: Авг. 1, 2023

We do not fully grasp viral droplet transmission processes in ventilated interior environments. The core focus of our research is to investigate the effectiveness protected occupied zone ventilation (POV) through computational fluid dynamics models a simplified office setting. large-eddy simulation technique with Eulerian–Lagrangian model was implemented address complicated indoor such as turbulence, flow–aerosol interaction, and impact. computationally investigated effects desk partitions POV on cough droplets an office. approach tested using two distinct exhaust layouts four different rates (1.0, 1.2, 1.5, 1.8 m/s). A comparative analysis flow fields, topologies, particle directions has been studied. findings indicate that plane jet's influence performance. distributed virus around room, but compared up-exhaust cases, down-exhaust cases appeared have better shielded healthy person. This pattern could placement outlet systems significantly influences aerosol dispersion. results also show substantial streams may carry tiny particles (≤70 μm) throughout their path. Large (≥100 go far gas clouds. Most deposit solid surfaces various work sites per specific rates. Office workers need be very cautious these hazardous areas.

Язык: Английский

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Numerical simulations of the flow and aerosol dispersion in a violent expiratory event: Outcomes of the “2022 International Computational Fluid Dynamics Challenge on violent expiratory events”

Physics of Fluids, Год журнала: 2023, Номер 35(4)

Опубликована: Март 11, 2023

This paper presents and discusses the results of “2022 International Computational Fluid Dynamics Challenge on violent expiratory events” aimed at assessing ability different computational codes turbulence models to reproduce flow generated by a rapid prototypical exhalation dispersion aerosol cloud it produces. Given common configuration, total 7 research teams from countries have performed 11 numerical simulations solving Unsteady Reynolds Averaged Navier–Stokes (URANS) or using Large-Eddy Simulations (LES) hybrid (URANS-LES) techniques. The each team been compared with other assessed against Direct Numerical Simulation (DNS) exact same flow. DNS are used as reference solution determine deviation modeling approach. both evaporative non-evaporative particle clouds has considered in 12 URANS LES. Most predict reasonably well shape horizontal vertical ranges buoyant thermal warm into an initially quiescent colder ambient. However, turbulent mixing is generally underpredicted, especially URANS-based simulations, independently specific model (and only lesser extent LES). In comparison DNS, approaches found overpredict range covered small that tends remain afloat within after injection ceased.

Язык: Английский

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Environmental data monitoring and infection risks in UK care-homes in the context of COVID-19

Building and Environment, Год журнала: 2024, Номер 250, С. 111174 - 111174

Опубликована: Янв. 8, 2024

The COVID-19 pandemic drew attention to the critical role of building ventilation as a measure for controlling infection transmission. With substantial number outbreaks in care homes worldwide, effectiveness is an important consideration control and wider exposure indoor air pollutants. In this study, we used IoT-based sensors two residential evaluate various areas, including bedrooms, corridors, communal spaces. Our monitoring focused on carbon dioxide (CO2) levels proxy ventilation, well temperature humidity, during spring 2022. We also developed model using software CONTAM coupled it with risk assess airborne transmission risks under different weather occupancy conditions. results suggest that generally adequate based UK guidelines at time, CO2 below 800 ppm majority opening windows spaces elderly environments can help preserve periods high occupancy. However, modelling data suggests low values may be indicative many therefore rates not sufficient mitigate Encouraging positive behaviours staff residents, potentially supported by visible monitors, taking additional precautions such cleaners, enabling window openings or wearing masks disease prevalence likely beneficial resident health.

Язык: Английский

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Advancing indoor risk mapping for virus transmission of infectious diseases through geographic scenario simulation

Cartography and Geographic Information Science, Год журнала: 2024, Номер 51(3), С. 421 - 444

Опубликована: Янв. 22, 2024

Close-range interpersonal interactions serve as a major channel for virus transmission, with higher infection risks indoors than outdoors. Thus, evaluating indoor infectious disease transmission is vital effective epidemic prevention and control. However, collecting complete individual-level behavioral data faces challenges due to privacy concerns acquisition costs, impeding accurate risk mapping. To address this, we propose an individual-centered, scenario-based simulation framework in this paper. This incorporates stepwise movement of agents model crowd spaces, enabling mapping through geographic scenario simulation. The model's core components encompass the generation environments, formulation individual behavior rules, establishment human-environment interaction logic, processes. Additionally, outline implementation algorithm model. Lastly, employ high-risk university canteen case study demonstrate capabilities creating maps at different levels: spatial, spatiotemporal, individual. proposed achieves construction process multi-dimensional scenarios microscale, introduces path based on spatiotemporal cubes, enhances comprehensive analysis risk, laying foundation precise

Язык: Английский

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Parametric study and optimization on exhaled particle dispersion in a ward heated by impinging jet ventilation using orthogonal-based grey relational method

Journal of Building Engineering, Год журнала: 2024, Номер 91, С. 109619 - 109619

Опубликована: Май 15, 2024

Язык: Английский

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Modeling the COVID-19 incorporating oil futures

Discover Analytics, Год журнала: 2025, Номер 3(1)

Опубликована: Янв. 30, 2025

Язык: Английский

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Learning from Immersive Augmented Reality on COVID-19 Transmission

Communications in computer and information science, Год журнала: 2025, Номер unknown, С. 399 - 413

Опубликована: Янв. 1, 2025

Язык: Английский

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Improving infectious bioaerosols removal in the ophthalmic negative-pressure operating room: The important role of air cleaners

Indoor and Built Environment, Год журнала: 2025, Номер unknown

Опубликована: Март 19, 2025

Infectious bioaerosols produced by patients pose a health threat to healthcare workers (HCWs) in ophthalmic negative pressure operating rooms (ORs). Thus, it is crucial understand the transport and deposition characteristics of infectious find ways improve their removal efficiency. In this work, numerical simulations negative-pressure OR were carried out using Eulerian–Lagrangian method. The airflow field bioaerosol distribution during surgery investigated. effectiveness an air cleaner (AC) enhance performance at different parameters was evaluated. results showed that AC ventilation inhibited diffusion particles formation high-concentration zones. HCW behind patient (HCW 1) faced higher exposure level than next 2). When velocity increased above 0.5 m/s, number inhaled, head-deposited body-deposited reduced more 88.3%, 76.5% 82.7%, respectively, for 1. improvement not significant when from m/s 0.7 m/s. Appropriately increasing temperature decreasing relative humidity reasonable option. Our findings provide useful insights developing rational mitigation strategies reducing cross-infection risk hospitals.

Язык: Английский

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