Numerical simulation and experiment of wind-sand movement characteristics around high vertical nylon mesh sand barriers

Abstract:This study aims to explore the movement law of wind and sand for the high vertical nylon mesh sand barrier, thereby to make up for the difficulty in the collecting data from field experiments, particularly on the sound reference for engineering sand control. Taking the Dengkou-Ustai sand-crossing highway as the background, a combination of the FLUENT numerical simulation and field test was used to investigate the design parameters of barrier rows, heights of sand barriers, and inlet wind speeds. A numerical simulation was carried out to obtain the change of wind speed, as well as the sand distribution of windward side, leeward side, and transition zone of net sand barrier. A field experiment was conducted to measure the specific parameters, and then the recorded data was later used for the error and linear correlation analysis. The results show that the air flow field in the horizontal direction represented in the form of "V" and "W" in the vertical sand barriers under different design parameters. The profile of wind speed shaped mainly in "S" for the transition zone of sand barriers. It infers that the wind speed has reversed airflow at this time, forming a vortex area or wind shadow area. The height of sand barrier directly determined the form and scope of flow field at the leeward side of sand barrier, as well as the cost of the project.When the wind speed is 8 m/s, as the number and height of barriers increased, the wind-proof effect became more obvious, and the amount of sand accumulation showed an increasing trend, and the influence ranges of single row, double row, three row sand barriers were from first row sand barrier to behind it 6, 13 and 20 m; when the wind speed is 10 m/s, as the height of the sand barrier increased, the airflow demarcation point gradually rised. The airflow demarcation points of sand barriers with heights 60, 100, 120, 150 cm were 0.8, 1.2, 1.5, 2.0 m, respectively. The airflow gradually returned to the wind speed in the wilderness, as the airflow moved away from the sand barrier. When the wind speed increased above 15m/s, the high vertical sand barrier gradually lost its protective effect. Error analysis was used to verify the high reliability of data, where the minimum relative error was 1.32%, the maximum relative error was 8.18%. The numerical model can be used to serve as an alternative approach for the insufficient data in field experiments. The combination of numerical simulation and field test can be used to mutually verify the optimal predict model in the preliminary screening for the indoor use, and acquire the movement rules of wind and sand, indicating an achievement can be gained in the effort at the field. The measurement cost normally was high, while the speed gradient of wind was not easy to measurement. A recommendation was made during this time that the design parameters can be reasonably selected according to the local wind conditions in the actual laying in the field.