In this paper, pollutants flows coming out of stacks or cooling towers with different outlet shapes have been numerically studied. The effects of exhaust outlet on plume rise, and the pollutant dissipation are investigated. To simulate the flow turbulence, realizable k – ε model is employed for the case of a stack flow with more than one exhaust outlet on the influence of wind condition. The plume rise and dissipation of pollutant are depending on the direction of the wind and the shape of exhaust outlet. Depending on wind direction and shape of exhaust outlet, higher or lower levels of plume rise can be obtained with various kind of pollutant dissipation. These changes are due to the influence of high pressure upstream and low-pressure downstream flow fields of outlet from stacks on the counter vertex rotating pair. The maximum concentration and dissipation of pollutant for various wind directions and output configurations are examined.