A 3D CFD model to assess the impact of the wind direction on the internal climate of poultry houses

To prevent the build-up of excess heat and noxious gases, the air inside livestock buildings must be exchanged on a regular basis. A successful use of natural ventilation to accomplish this task depends on reliable measurements of outside wind velocity and direction, as both mainly control the internal air renewal rate of the building. To accomplish the required analyses, the present work relied on a study that used computational fluid dynamics (CFD) to replicate the internal climate dynamics of a typical poultry house. The model developed in this study focused on solving the equations that govern momentum, heat and mass transport and also included data pertaining to radiative transfers and animal-generated heat. The study considered three fixed angles of wind direction (0°, 36° & 56°- with 0° corresponding to wind blowing perpendicular to the ridgeline). A wind blowing at an angle of 36° was chosen to validate the model against experimental data. CFD predictions achieved a RMSE of 1.2°C and 0.6 g [H2O] kg-1 [dry air] for internal temperature and absolute humidity; respectively. Consequently, the same 3D CFD model (with the same input key climatic variables) was used to predict the impact of two additional fixed-wind directions (0° & 56°). Predictions achieved by the model were used to assess the potential change in capacity of the poultry house to renew air, and it was found that during a period of 3h, the air renewal rate oscillated from 39.5 (±1.9), 34.9 (±2.2) and 33.6 (±1.7) air exchanges per hour when air blew at 0°, 36° and 56°; respectively. These outcomes can serve to determine the range of wind directions that could imperil animals housed in naturally ventilated buildings.