These model experiments of air flow characteristics suggest that when swine confinement buildings are oriented so that the approaching wind is parallel to the buildings the wind is reduced less than when the buildings are oriented across the wind direction. This can be attributed to the smaller frontal area of the buildings blocking the wind (ends of buildings vs. sides of buildings facing the wind) and differences in air flow patterns. It is likely that the parallel buildings cause acceleration of the wind between them and toward the downwind slurry tank or lagoon. By comparison, the sloping roof of buildings perpendicular to the wind direction forces the air up and around the ends of the buildings and away from the slurry tank or lagoon. These changes in wind speed, wind direction and mixing may all have potential impact on odor constituent transport from manure storage structures.
Results of these experiments suggest that orienting swine production buildings so that they are perpendicular to prevailing wind direction may reduce odor transport from a downwind slurry tank or lagoon, especially if the manure storage unit is close to multiple buildings. However, these studies were completed with steady wind and unchanging wind direction so results under field conditions may be somewhat different than these wind tunnel results and should be verified by field measurements. The wind tunnel experiments also indicate that upwind building effects on odor constituent transport from slurry tanks is not affected as much as that from lagoons and that buildings upwind will tend to increase transport from a lagoon. Experiments simulating the effects of trees or a hill up or downwind from the production facility gave unexpected results. Even though trees upwind will slow down the wind, this did not always result in a reduction in evaporation from downwind slurry tanks or lagoons. This study demonstrated that the complicated effects of buildings on air flow make generalizations about their effects on downwind processes difficult.
