Goyal and Khare, J Civil Environ Eng 2012, S:1 DOI: 10.4172/2165-784X.S1-001 Research Article Open Access J Civil Environ Eng ISSN: 2165-784X JCEE, an open access journal Urban Air Pollution: Measurements, Physicochemical Characteristics, Exposure, Health and Dispersion Modelling Simulation of Airflow and Wind Pressure Coefficient in a Naturally Ventilated Classroom Model Using Environmental Wind Tunnel and CFD Modelling Radha Goyal 1 * and Mukesh Khare 2 1 Scientist Fellow, National Environmental Engineering Research Institute (NEERI), Delhi Zonal Laboratory, CSIR R&D centre, Naraina Industrial Area, Delhi, India 2 Professor, Department of Civil Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, India Abstract The article presents an experimental study, which has been carried out in an environmental wind tunnel to measure the mean pressures and pressure differences at inlet and outlet of various openings of a naturally ventilated classroom model of a school building located near an urban roadway in the city of Delhi. The wind pressure coeffcients have been measured and analyzed for different wind incidence angles and for varying classroom opening confgurations representing the change in behavior of building occupants in different seasons of the year. The article also presents the results of a CFD modeling carried out to estimate the wind velocity and turbulent intensity in and around the classroom model to understand the actual airfow pattern inside the classroom. The present study is an effort to understand the occurrence of ventilation in naturally ventilated buildings and fnally to evaluate the indoor air quality in such buildings. *Corresponding author: Radha Goyal, Scientist Fellow, National Environmental Engineering Research Institute (NEERI), Delhi Zonal Laboratory, CSIR R&D centre, Naraina Industrial Area, Delhi, India, E-mail: Sunday.oyedepo@covenantuniversity.edu.ng Received July 27, 2012; Accepted August 26, 2012; Published September 10, 2012 Citation: Goyal R, Khare M (2012) Simulation of Airfow and Wind Pressure Coeffcient in a Naturally Ventilated Classroom Model Using Environmental Wind Tunnel and CFD Modelling. J Civil Environ Eng S1:001. doi:10.4172/2165-784X. S1-001 Copyright: © 2012 Goyal, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: Naturally Ventilated Buildings; Wind Pressure Coefcient; Environmental Wind Tunnel; Computational Fluid Dynamics; Indoor Air Quality Introduction Urban areas are increasingly becoming polluted with increase in the number of industries, vehicles along with factors like reduction in forested areas to make way for various activities. Tis makes indoor spaces in urban areas prone to pollutants from outside which is compounded by factors like defects and leakage in buildings as well as climatic conditions which may transfer the pollutants from outside to the interiors. Natural ventilation in buildings can create a comfortable and healthy indoor environment. It replaces indoor polluted air with fresh outdoor air without using mechanical power and thus save the energy consumed by the heating, ventilating and air-conditioning systems in a building if it provides acceptable indoor air quality (IAQ) and thermal comfort levels [1]. In a naturally ventilated building, air is driven in and out due to pressure diference produced by wind or buoyancy forces. Tough natural ventilation is conceptually simple, its detailed design as the ventilation performance can be a challenge as intake air is not usually controlled and it involves the infuence of building’s type, its surroundings and climate. It is even more difcult in cases of wind driven ventilation, where efects of turbulence dominate [2,3]. Wind causes variable surface pressures on building’s exterior surface that depends on the wind direction and speed, air density, surface orientation, and surrounding conditions. It changes the intake and exhaust system fow rates, infltration, exfltration and interior pressures in the buildings and therefore becomes the predominant driving force for ventilation [4]. Terefore, investigation of wind pressure distributions on buildings and the infuence of environmental factors on it is an important feld of investigation to understand the working of natural ventilation. Some researchers have tried to determine pressure profles on buildings for diferent incidences [5,6], neighbor buildings confgurations [7] or local environment densities [8]. Others try to describe buildings or topography infuence on wind fow [9,10]. Some have investigated particular confgurations as street canyon [11]. However, a systematic approach is necessary to obtain efective comprehension of pressure distributions on buildings to evaluate the IAQ as well as of thermal comfort levels of the buildings. Te above studies have also shown that the onsite measurement of airfow characteristics and the interpretation of its role in ventilation efectiveness is a very difcult task in naturally ventilated structures. Terefore, various models and tools have been used by building designers, IAQ and comfort experts to estimate the airfow rate, the dispersion of contaminants and the ventilation efciency. Tese models range from simple empirical algorithms to calculate the global airfow rate to sophisticated CFD techniques based on Reynolds averaged Navier–Stokes (RANS) method [12-14]. In present study, an efort has been made to calculate the wind pressure coefcients (Cp) at the interior and exterior of the openings in a naturally ventilated classroom. An environmental wind tunnel (EWT) study has been carried out for simulation of pressure distribution inside and outside the classroom of a naturally ventilated school building, pressure coefcient (Cp) and airfow pattern with varying classroom conditions e.g. in fully and partially opened, and fully closed windows and doors. An alternative computational fuid dynamic (CFD) modeling has also been carried out to calculate the wind velocity and turbulent intensity and to observe the airfow distributions in and around the classroom model. Site Selection and Experimental Setup A low rise (three-story) naturally ventilated school building located near a busy road and a fy over in urban vicinity and surrounded by commercial and residential area has been selected for the study. Te classrooms selected for wind tunnel study are with dimensions of 7.57 m×6.02 m×3.90 m. Each classroom is having three windows J o u r n a l o f C i v il & E n v i r o n m e n t a l E n g i n e e r i n g ISSN: 2165-784X Journal of Civil & Environmental Engineering