Numerical investigation of wind-induced airflow and interunit dispersion characteristics in multistory residential buildings.

Compared with the buoyancy-dominated upward spread, the interunit dispersion of pollutants in wind-dominated conditions is expected to be more complex and multiple. The aim of this study is to investigate the wind-induced airflow and interunit pollutant dispersion in typical multistory residential buildings using computational fluid dynamics. The mathematical model used is the nonstandard k-ε model incorporated with a two-layer near-wall modification, which is validated against experiments of previous investigators. Using tracer gas technique, the reentry of exhaust air from each distinct unit to other units on the same building, under different practical conditions, is quantified, and then, the possible dispersion routes are revealed. The units on the floor immediately below the source on the windward side, and vertically above it on the leeward side, where the reentry ratios are up to 4.8% and 14.9%, respectively, should be included on the high-infection list. It is also found that the presence of balconies results in a more turbulent near-wall flow field, which in turn significantly changes the reentry characteristics. Comparison of the dispersion characteristics of the slab-like building and the more complicated building in cross (#) floorplan concludes that distinctive infectious control measures should be implemented in these two types of buildings.

[1]  J Niu,et al.  On-site quantification of re-entry ratio of ventilation exhausts in multi-family residential buildings and implications. , 2007, Indoor air.

[2]  Cheuk Ming Mak,et al.  The Effect of Balconies on Ventilation Performance of Low-rise Buildings , 2011 .

[3]  Yoshihide Tominaga,et al.  Turbulent Schmidt numbers for CFD analysis with various types of flowfield , 2007 .

[4]  Koichi Sada,et al.  Numerical calculation of flow and stack-gas concentration fluctuation around a cubical building , 2002 .

[5]  S. Orszag,et al.  Renormalization group analysis of turbulence. I. Basic theory , 1986 .

[6]  John Burnett,et al.  Wind-induced pressure at external surfaces of a high-rise residential building in Hong Kong , 2005 .

[7]  Richard Griffiths,et al.  Field experiments of dispersion through regular arrays of cubic structures , 1997 .

[8]  W. H. Engelmann,et al.  The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants , 2001, Journal of Exposure Analysis and Environmental Epidemiology.

[9]  Theodore Stathopoulos,et al.  Near-field pollutant dispersion in the built environment by CFD and wind tunnel simulations , 2011 .

[10]  J. Niu,et al.  Investigation of indoor air pollutant dispersion and cross-contamination around a typical high-rise residential building : wind tunnel tests , 2010 .

[11]  Ilias Mavroidis,et al.  Numerical simulation of flow and dispersion around an isolated cubical building: The effect of the atmospheric stratification , 2009 .

[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]  Y. Tominaga,et al.  Numerical simulation of dispersion around an isolated cubic building: Model evaluation of RANS and LES , 2010 .

[14]  S. Murakami,et al.  Comparison of various revised k–ε models and LES applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer , 2008 .

[15]  M. Santamouris,et al.  Experimental investigation of air flow and temperature distribution in deep urban canyons for natural ventilation purposes , 2006 .

[16]  Frank Thiele,et al.  Comparison of LES and RANS in bluff-body flows , 2001 .

[17]  Shuzo Murakami,et al.  Overview of turbulence models applied in CWE–1997 , 1998 .

[18]  J. L. Niu,et al.  Assessment of Pollutant Dispersion in the Re-entrance Space of a High-rise Residential Building, Using Wind Tunnel Simulations , 2010 .

[19]  S. Murakami,et al.  Development of a new k−ε model for flow and pressure fields around bluff body , 1997 .

[20]  Richard Griffiths,et al.  Wind tunnel modelling of urban building exposure to outdoor pollution , 2005 .

[21]  M. Wolfshtein.  The velocity and temperature distribution in one-dimensional flow with turbulence augmentation and pressure gradient , 1969 .

[22]  Theodore Stathopoulos,et al.  Numerical evaluation of pollutant dispersion in the built environment: comparisons between models and experiments , 2008 .

[23]  Qingyan Chen,et al.  Natural Ventilation in Buildings: Measurement in a Wind Tunnel and Numerical Simulation with Large Eddy Simulation , 2003 .

[24]  Yoshihide Tominaga,et al.  Numerical simulation of dispersion around an isolated cubic building: Comparison of various types of k–ɛ models , 2009 .

[25]  Mats Sandberg,et al.  The influence of building height variability on pollutant dispersion and pedestrian ventilation in idealized high-rise urban areas , 2012 .

[26]  Ryuichiro Yoshie,et al.  CFD simulations of gas dispersion around high-rise building in non-isothermal boundary layer , 2011 .

[27]  Paul Fazio,et al.  The influence of turbulent wind on air change rates—a modelling approach , 1991 .