AIRFLOW AROUND AGRICULTURAL BUILDINGS: MEASUREMENTS IN A WIND TUNNEL AND DIRECT NUMERICAL SIMULATION

Building designs influence the external airflow field and the internal environment. Airflow around a building structure is important for design and control of ventilation as well as the exhaust air dispersion. In this work, an analysis of complex airflow around two agricultural buildings with different roof geometry is presented. The building models with arched-type or pitched-type roof were used in wind tunnel measurements. The two-dimensional, turbulent, separated or reattached airflow, around the building models, was investigated with the direct numerical solution of Navier-Stokes (N-S) and continuity equations using the finite element method. Instantaneous values of air velocity were obtained from the numerical solution of the time-dependent model. The air velocities were used to present a dynamic and statistical analysis of this complex flow. The roof geometries affected the instantaneous and time averaged flow velocity. The phenomena that characterize such flows are unsteady, with severe disruptions in the airflow, even for very low velocities because of the existence of the building, which is an obstacle to the flow. Due to the small Reynolds number, experimental validation of the numerical results was performed in a wind tunnel. Good agreement was achieved between the numerical simulation results and wind tunnel measurements with respect to velocity distributions confirming the accuracy of the numerical model. The dynamic approach of the flow parameters introduces important information on instantaneous fluctuations of the complex flow phenomena around agricultural buildings, which can be ignored by time-mean averaged data. The studied turbulent model can be used in any agricultural building, providing reliable and useful results about the flow field around greenhouses or livestock buildings.