Our work consisted in carrying out an experimental investigation in order to study the structure of the flow field issuing from a bent chimney and deviated when meeting a parallelepiped obstacle. For the matter we used: the Particle Image Velocimetry (PIV). A parallel numeric simulation of the problem was also elaborated and compared with the above mentioned experimental results. A three-dimensional numerical model based on the RMS turbulence closure model was used. The adopted grid is not uniform, particularly refined near the chimney and around the obstacle. A good level of agreement was achieved between the experimental data and numerical calculations. Once the model validated, we studied the effects of the distance separating the chimney and the obstacle. The tested values are Dch-obs= 10 cm and Dch-obs= 20 cm.