Effects of gravel coverage on CFD-based near-surface wind field
Zhao Wenju1, Song Jianshu1, Ma Xiaoyi2, Zhao Tinghong1
1.School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2.Key Laboratory for Agricultural Soil and Water Engineering in Arid Area of Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China
Abstract：Wind erosion is one of the main reasons for land desertification in Northwest China. To su-ppress the desertification progress and promote both agricultural and livestock production, many protective measures, such as gravel and vegetation coverage, crop stubble and so on, have been applied in barren lands in Northwest China. In consequence, the near-surface wind field was improved significantly and the wind erosion has been reduced effectively, and the soil moisture has been maintained, eventually the land degradation has been slowed down. In the paper, the three-dimensional, steady near-surface wind fields around a series of gravel coverage were simulated by CFD method for 2.0 mm-12.0 mm gravel size at 5 m/s and 13 m/s wind speeds, respectively; meanwhile, field observations were conducted. The results show that at the same height above the ground the degree of reduction of near-surface wind velocity rises with increasing gravel size until the size reaches 10.0 mm; once the size is beyond that value, the degree doesn't change with gravel size basically. The increment in degree of reduction of wind velocity increases with gravel size; moreover, at the same gravel size, the degree of reduction decreases with height apart from the ground. It was found out that the degree of reduction of wind velocity is insensitive to change in wind velocity by comparing the results at 5 m/s and 13 m/s wind speeds. The predicted degree of reduction of wind speed matches the field observation as good as more than 89%. This study can provide a theoretical basis for development of ecological agriculture in an arid area.
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