The influence of human walking on the flow and airborne transmission in a six-bed isolation room: Tracer gas simulation

Abstract By performing unsteady CFD simulations using RNG k–ɛ model and dynamic mesh technique, this paper investigates how the walking motion of health care worker (HCW) influences gaseous dispersion in a six-bed isolation room with nine downward supplies and six ceiling-level or floor-level exhausts. The flow near and behind HCW is easily affected by HCW motion. The flow disturbance induced by HCW walking with swinging arms and legs is a mixing process. The walking HCW displaces air in front of it and carries air in the wake forwardly, meanwhile pressure difference drives air from two lateral sides into the wake. HCW motion (0–5.4 s) indeed induces a little gaseous dispersion, but the residual flow disturbance after HCW stops (5.4 s–25.4 s) induces more gaseous agent spread and it requires more than 30–60 s to approximately recover to the initial state after HCW stops. Although HCW motion indeed affects airborne transmission, but its effect is less important than ventilation design. No matter with or without HCW motion, the ceiling-level exhausts perform much better in controlling airborne transmission than the floor-level exhausts with the same air change rate (12.9 ACH). Smaller air change rate of 6 ACH experiences higher concentration and more gaseous spread than 12.9 ACH. In contrast to the realistic human walking, the simplified motion of a rectangular block produces stronger flow disturbance. Finally surface heating of HCW produces a stronger thermal body plume and enhances turbulence near HCW, thus slightly strengthens airborne transmission.

[1]  P V Nielsen,et al.  Dispersal of exhaled air and personal exposure in displacement ventilated rooms. , 2002, Indoor air.

[2]  Qingyan Chen,et al.  Impact of Moving Objects onContaminant Concentration Distributions in an Inpatient Ward with Displacement Ventilation , 2010 .

[3]  Sangsan Lee,et al.  Unsteady aerodynamic force prediction on a square cylinder using k−ε turbulence models , 1997 .

[4]  I Eames,et al.  Movement of airborne contaminants in a hospital isolation room , 2009, Journal of The Royal Society Interface.

[5]  Tin-Tai Chow,et al.  Numerical investigation of influence of human walking on dispersion and deposition of expiratory droplets in airborne infection isolation room , 2011 .

[6]  Hiroshi Matsumoto,et al.  The Influence of a Moving Object on Air Distribution in Displacement Ventilated Rooms , 2004 .

[7]  Sophie Papst,et al.  Computational Methods For Fluid Dynamics , 2016 .

[8]  A. Lai.  Particle deposition indoors: a review. , 2002, Indoor air.

[9]  Sastry S. Isukapalli,et al.  Impact of scaling and body movement on contaminant transport in airliner cabins , 2011 .

[10]  Peter V. Nielsen,et al.  Dispersion of exhalation pollutants in a two-bed hospital ward with a downward ventilation system , 2008 .

[11]  Qingyan Chen,et al.  Distributions of respiratory contaminants from a patient with different postures and exhaling modes in a single-bed inpatient room , 2010, Building and Environment.

[12]  P. Heiselberg,et al.  The airborne transmission of infection between flats in high-rise residential buildings: Tracer gas simulation , 2007, Building and Environment.

[13]  Bin Zhao,et al.  Role of two-way airflow owing to temperature difference in severe acute respiratory syndrome transmission: revisiting the largest nosocomial severe acute respiratory syndrome outbreak in Hong Kong , 2011, Journal of The Royal Society Interface.

[14]  Bin Zhao,et al.  Some questions on dispersion of human exhaled droplets in ventilation room: answers from numerical investigation. , 2010, Indoor air.

[15]  Chao-Hsin Lin,et al.  Flow dynamics and characterization of a cough. , 2009, Indoor air.

[16]  E. A. Hathway,et al.  The ventilation of multiple-bed hospital wards: review and analysis. , 2008, American journal of infection control.

[17]  Yang-Cheng Shih,et al.  Numerical study on the dispersion of airborne contaminants from an isolation room in the case of door opening , 2008, Applied Thermal Engineering.

[18]  Henrik Brohus,et al.  Personal Exposure in Displacement Ventilated Rooms , 1996 .

[19]  J. Edwards,et al.  Large-eddy simulation of human-induced contaminant transport in room compartments. , 2012, Indoor air.

[20]  Magnus Mattsson.  On the efficiency of displacement ventilation , 1999 .

[21]  B E Ainsworth,et al.  Compendium of physical activities: an update of activity codes and MET intensities. , 2000, Medicine and science in sports and exercise.

[22]  I. Eames,et al.  Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises , 2006, Journal of Hospital Infection.

[23]  H. Qian,et al.  Removal of exhaled particles by ventilation and deposition in a multibed airborne infection isolation room. , 2010, Indoor air.

[24]  P V Nielsen,et al.  Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems. , 2006, Indoor air.

[25]  J. Edwards,et al.  Large eddy simulation and zonal modeling of human-induced contaminant transport. , 2008, Indoor air.

[26]  Qingyan Chen,et al.  Ventilation performance prediction for buildings: A method overview and recent applications , 2009 .

[27]  Chao-Hsin Lin,et al.  Characterizing exhaled airflow from breathing and talking. , 2010, Indoor air.

[28]  Bin Zhao,et al.  Numerical Investigation of Particle Diffusion in a Clean Room , 2005 .

[29]  Zhiqiang John Zhai,et al.  Evaluation of Various Turbulence Models in Predicting Airflow and Turbulence in Enclosed Environments by CFD: Part 2—Comparison with Experimental Data from Literature , 2007 .

[30]  W. Nazaroff.  Indoor particle dynamics. , 2004, Indoor air.

[31]  Ronan Boulic,et al.  Versatile walk engine , 2004, J. Game Dev..

[32]  Zhao Zhang,et al.  Experimental and numerical investigation of airflow and contaminant transport in an airliner cabin mockup , 2009 .

[33]  Y. Li,et al.  Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong. , 2005, Indoor air.

[34]  Qingyan Chen,et al.  Flow and contaminant transport in an airliner cabin induced by a moving body: Model experiments and CFD predictions , 2010 .

[35]  Bin Zhao,et al.  Numerical study of the transport of droplets or particles generated by respiratory system indoors , 2004, Building and Environment.

[36]  Yang-Cheng Shih,et al.  Dynamic airflow simulation within an isolation room , 2006, Building and Environment.

[37]  Jeanine Weekes Schroer,et al.  The Finite String Newsletter Abstracts of Current Literature Glisp User's Manual , 2022 .

[38]  Qingyan Chen,et al.  Experimental Study on Displacement and Mixing Ventilation Systems for a Patient Ward , 2009 .

[39]  A. Nicolle,et al.  Observing and quantifying airflows in the infection control of aerosol- and airborne-transmitted diseases: an overview of approaches , 2010, Journal of Hospital Infection.

[40]  Shih-Cheng Hu,et al.  An experimental study on ventilation efficiency of isolation room , 2009 .

[41]  Henrik Brohus,et al.  Personal Exposure to Contaminant Sources in Ventilated Rooms , 1997 .

[42]  P V Nielsen,et al.  Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review. , 2007, Indoor air.

[43]  Naiping Gao,et al.  CFD study on the transmission of indoor pollutants under personalized ventilation , 2013 .

[44]  Bin Zhao,et al.  Comparison of indoor aerosol particle concentration and deposition in different ventilated rooms by numerical method , 2004 .

[45]  Zhao Zhang,et al.  State-of-the-art methods for studying air distributions in commercial airliner cabins , 2011, Building and Environment.

[46]  Peter C Raynor,et al.  A performance assessment of airborne infection isolation rooms. , 2007, American journal of infection control.

[47]  Ian Eames,et al.  Door-opening motion can potentially lead to a transient breakdown in negative-pressure isolation conditions: the importance of vorticity and buoyancy airflows , 2005, Journal of Hospital Infection.

[48]  Gary S. Settles,et al.  Computational Study of the Wake and Contaminant Transport of a Walking Human , 2005 .

[49]  J. Niu,et al.  CFD Study of the Thermal Environment around a Human Body : A Review , 2005 .