Wind Tunnel Evaluation of Vegetative Buffer Effects on Air Flow near Swine Production Facilities

Scale model wind tunnel experiments were completed to complement field monitoring and economic analyses to determine the effectiveness and feasibility of vegetative buffers to mitigate swine odor and particulate transport. Three series of wind tunnel experiments were completed. The first included 4 swine housing unit models and either a slurry tank or lagoon model downstream. Evaporation from the tank and lagoon models was monitored during runs with 0.5 and 2 m/s air velocities and parallel and transverse building orientations. Runs were completed with and without 5.25 mm-tall (2“) tree models constructed from 8 x 8 wire mesh to simulate forested terrain. A model forest consisting of 8 rows of trees perpendicular to air flow was positioned upstream of the building models and downstream of the manure storage models. The second series of experiments included air velocity profile measurements near a scale-model of an actual deep pit production facility with 3 buildings and 2 rows of trees on 2 sides. Measurements were taken with air velocities of 0.5, 2, and 5 m/s at separation distances of 1, 2, and 6 x's the building height. The third study included similar velocity profile measurements but for a field site with ongoing odor and particulate monitoring. Tree models spacing and orientation were then manipulated to attempt to develop an optimal arrangement for air flow management at the facility. Results from each study will be interpreted with regard to the impact of vegetative buffers on air flow, the effect on transport from manure storage structures, and prospects for optimizing buffer design to minimize offsite odor and particulate transport.