Volume No. 4 Issue No.: 1 Page No.: 222-231 July-Sept 2009

 

A COMPARISON OF RESULTS FROM FIELD AND WIND TUNNEL MODELLING OF DISPERSION IN ARRAYS OF OBSTACLES

 

Krishna M. K* and Mahalingegowda R. M

Department of Environmental Engineering, P. E. S. College of Engineering,
Mandya-571401, Karnataka, (INDIA).

 

Received on : May 15, 2009

 

ABSTRACT

 

To evaluate the dispersion profiles in vertical and downwind distance, twenty one experiments were conducted in the three simulated Atmospheric Boundary Layers (ABLs). The dispersions showed that with increase in height the concentration is decreasing. The normalised concentrations verses downwind distance drawn and fitted a best fit curve (power law). The pollutant dispersion is high at the ground and near to the source. This may be due to the fact that turbulence level is higher near to the ground level. Plume dispersion around urban buildings has been investigated by physical modeling using arrays of building-like obstacles at scales-1: 100 in a boundary layer wind tunnel. The models were laid out on a surface of length 4.8 m along x-axis. Dispersion experiments were carried out within the boundary layer in the downwind part of the working section at fan speed 1.8 m/s to produce a reference wind speed. Dispersion experiments shows that concentration profiles follow almost the same trend as that reported in wind tunnel study Ahmad1. Also vertical plume, compared with field and wind tunnel values reported by Macdonald2, it shows that wind tunnel data’S of Macdonald and present work is showing same trend.

 

Keywords : Environmental wind tunnel, Atmospheric Boundary Layers, Urban pollution.

 

 

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