Abstract:

One of the important measures to control sand disasters in western desert areas is sand fixation by plants. As a typical desert plant, Alhagi camelorum has important application value. Based on the flow field in the spring, 30 cm of dry Alhagi camelorum was the object of research in this paper. To analyze the characteristics of wind speed and sand deposition, a numerical simulation was used via the fluent and field tests. The results were as follows: (1) the wind-sand flow can be roughly divided into the areas of blocked deceleration, lifting acceleration, turbulent deceleration, and recovery when going through the plant. A weak vortex forms behind the plant, and the height of the recirculation region is related to the distance from the plant. However, they are less than 0.14 m. (2) When the wind speed is 6 m∙s^-1, plants at a height of 30 cm mainly affect the horizontal wind speed below a height of 0.6 m. The horizontal wind speed at a certain distance behind the plant no longer presents a strict logarithmic distribution with height, but there are two minima, and the acceleration increases rapidly in the height range of 0.3-0.6 m. (3) The windproof efficiency of plants decreases with the increase of wind speed, and this phenomenon becomes more and more obvious the height increases. When the wind speed increases from 6 to 10 m∙s^-1, the windproof efficiency at a height of 0.3 m within a distance of 5.3 m behind the plant decreases from 40% to 16.56%. (4) The sand accumulation near the plant is different due to the different wind speed. When the wind speed of the incoming flow is low, sand accumulation is mainly concentrated near the front of the plant and within the range between plants. As wind speed increases, sand accumulation moves backward.

Key words: sand-fixing service, flow field distribution, numerical simulation, Alhagi camelorum, vortex