investigation of dissipation flow in the urban canyon

with the wind permanent flow in the cities, obtaining the minimal pollution in the environment is accessible. different policies have been considered for optimization of cities such as attachment and or reduction of building parts like air-traps, ceiling forms and so on. due to population growth in cities and the increasing need for resettlement these people in the cities, inevitably, to the high-rise buildings have gone. the people living in high-rise buildings to meet the needs of their vital urban open spaces are forced to use. to have knowledge about air pollution through buildings, the cfd based software of envi-met is used. in this case, we can say that the best angle to transfer pollution is the angle of 30 degrees. also in an ideal case with imposed changes in the form, we could enhance the problem by better navigation of inside wind of urban canyons into spaces between blocks of buildings that have the capacity to trap the particles. final it is found that we may be able to have more optimal results for transition of pollutions by suitable orientation of blocks against the wind direction of blow.