Research On The Wind-blown Sand Movement Around The Desert Highway And Wind-break Wall

In recent years, wind erosion makes a great damage of the desert highway, so it is a key problem to be solved. Using the normal κ-ε model, this paper simulated the wind field and calculated the structural characteristics of the wind field around the desert highway by the commercial CFD software Fluent. And the simulation results can explain sand erosion in the area of embankment and sand accumulation in the deceleration zone. Similarly, using the normal κ-ε model and grain track equations, this paper simulated the wind field and calculated the structural characteristics of the wind field around the desert highway with the wind-break wall. Also, the trajectory of sands in different diameter, under different friction velocity is calculated when different height for the wind-break wall is choosed. Based on the simulation results, research is conducted on the mechanism and performance of the wind-break wall, and some references and advices are put forward to design and build the wall in engineering.The paper consists of two main parts. The first part is the simulation of wind field around the highway bank, while the second part is the simulation of wind field around the bank with a windbreak wall under different incoming velocity. After obtaining the wind field, the trajectories of sand in different diameter are studied by Discrete Phase Model in Fluent. In the simulation of second part, different distance from the wall to the bank, different wall height, different sand diameter are utilized. Through the simulation, three conclusions are obtained.1. The wind accelerates in the up and top part of the windward of the highway bank, and causes serious erosion on the bank. And, deceleration exists in the road face, the foot of windward side and the foot of the leeward side. The sands would slow down in these zones and the accumulation came into being.2. The wind field around the bank varies seriously after setting a windbreak wall. Based on the simulation results and the engineering experience, there are several criterions about the reasonable distance from the wind-break wall to the highway bank. Firstly, most of the sands should be kept in the incoming side of the windbreak wall. Secondly, there is no acceleration zone in the windward of the bank and no erosion on the road face. Thirdly, the wind-blown sand can pass the highway bank steadily. Through the simulation of trajectories of sands in different wind field, with different diameter and different wall height by Discrete Phase Model in Fluent, it is found that the performance of wind-break wall is best when the height is2meters and the distance from the wall to the bank is3meters.3. Given the certain height of the wind-break wall, the performance of the wall is different under different initial incoming velocity. When the incoming velocity is too low, the performance is too poor. While, the vortex zone is too big with a too-high incoming velocity. Given the certain incoming velocity, when the wall height increases, more sands are blown up for the sands coming from high entrance, and there is little effect for the wind field behind the wall and the sand movement. In conclusion, considering the performance of wind-break wall and the cost, the performance is best when the wall height is a little higher than the highway bank in engineering.