Wind Turbulence in a Soybean Field Sheltered by Four Types of Wind Barriers
1974
Radke, J. K. | Hagstrom, R. T.
Crop yields and quality are frequently improved when the crop is sheltered by temporary, field wind barriers. To better understand the influence of temporary wind barriers on the microclimate, plant-water relations, and crop yield, it is necessary to understand the effect of wind barriers on wind structure and turbulence. Several mathematical and statistical functions characterizing wind turbulence were determined for four types of wind barriers from hot-film anemometer signals fed into a real-time correlator with subsequent computer analysis. Wind barriers tested were double rows of corn (Zea mays L.), double rows of sunflowers (Helianthus annuus L.), a snowfence, and a solid board fence. The wind structure and turbulence parameters were always different behind the solid barrier compared to the porous barriers because the wind had to go up and over the top of the solid barrier. The porous barriers broke up the larger eddies into smaller eddies, decreased the wind velocity, and reduced the amount of energy at the lower frequencies. In general, the crop barriers gave results similar to those for snowfence for velocity but were different for energy, frequency, and scale considerations. The crop barrier leaves fluttered, causing greater energy dissipation and the generation of new distinctive frequencies. The corn and sunflowers gave similar results, although the sunflower barriers tended to be like a solid barrier because of their denser canopy.
显示更多 [+] 显示较少 [-]