CFD Analysis to Predict Close Range Spreading of Ventilation Air from Livestock Buildings

Odour annoyance from livestock production is an increasing problem in many countries, and efforts to reduce the odour inconvenience are necessary to maintain or establish good relations between animal producers and their neighbours. Ventilation exhaust is usually the most significant odour source from livestock production and full scale tracer gas measurements shows that the location and design of exhaust have a significant influence on the spreading and distribution of exhausted air in the close surroundings. The paper describes a CFD (Computational Fluid Dynamics) model to investigate the possibilities to reduce odour concentrations by optimising the location and design of exhausts. The CFD model was validated against full scale tracer gas measurements around a commercial growing-finishing pig building and subsequently the model was used to investigate how six different exhaust configurations is expected to influences the concentration of exhausted air at neighbours located at two different distances from a production unit. Comparison with the full scale tracer gas measurements indicated that the used CFD-method is a suitable technique to predict the spreading of exhausted air 50 to 150 m form a livestock building. The investigation of the six different exhaust configuration demonstrated that a change in the location or layout of exhausts can have a significant influence on the exposure of exhausted air at down wind located neighbours.