Wind-sand Flow Research Articles

Analysis and Application of Particle Backtracking Algorithm in Wind–Sand Two-Phase Flow Using SPH Method

Due to the high sensitivity of grid-based micro-scale wind–sand flow models to deformation and distortion, this study employs the Smooth Particle Hydrodynamics (SPH) method for numerical simulations. The advantage of the SPH method is that it can dynamically analyze the entire trajectory of the particles, thus allowing the initial positional distribution of sand-buried particles to be traced. This study utilizes the advantages of the SPH method. It develops particle backtracking algorithms based on the SPH method using the C language. It analyses the initial location distribution, concentration, velocity, and particle size distribution of sand-buried particles to formulate targeted measures to cope with wind–sand disasters. Meanwhile, this paper improves a particle modeling algorithm to realize arbitrary mixing particle size and mixing ratio by programming in C language and combining it with pixel recognition technology. In addition, this paper will use the particle backtracking algorithm to analyze the classical embankment wind and sand flow field and then propose adequate measures for embankment wind and sand disaster management by investigating sand particle movement characteristics.

Blown sand environment characteristics and bridge sand hazard mechanisms of expressways in the South Tibet Valley.

South Tibet expressways are built in the Yalu Tsangpo valley along the route to high-altitude and cold-temperature valleys, which are the main environmental characteristics of the region. Given that the blown sand environment and its potential harm are unclear, targeted prevention and control are not conducive, but its absence would result in severe wind-sand hazards on these expressways. In this research, the blown sand environment of the South Tibet Valley and the mechanism of sand damage to expressway bridges were studied via field observations, wind tunnel experiments and numerical simulations. The sand-moving wind is mainly west wind. The sand-moving wind frequency, sand drift potential, and maximum possible sand transport quantity are high in winter and spring (November-April) and low in summer and autumn (May-October). The sand drift direction is in the east direction. Expressway bridges have a considerable impact on the near-surface blown sand environment, forming a zone for increasing the wind speed between the top of the slope shoulder of the windward side of the bridge to the center of the bridge abutment, forming a zone for weakening the wind speed between the - 3H distances of the upwind direction to the bottom of the slope middle of the windward side of the bridge, further forming a zone for weakening the wind speed centered in the slope shoulder of the leeward side of the bridge. The wind speed within a distance of 40H downwind direction of the bridge generally did not recover. The wind-sand flow is partially blocked when it passes through the bridge and accumulates near the bridge, which cause harm. The impact of the bridge on the blown sand environment in the downwind is greater than that in the upwind. The results of this study can provide a reference for preventing and controlling wind-sand hazards on South Tibet expressways.

Research on the Dynamic Response of High-speed Trains under Different Curve Radii Caused by Wind–sand Flow

Research on the Dynamic Response of High-speed Trains under Different Curve Radii Caused by Wind–sand Flow

Research on wind turbine blade coating erosion modeling based on Generic modeling

Abstract In order to improve the accuracy of the prediction of the erosion phenomenon of wind turbine blade coatings, this study incorporates the wind-sand erosion data of wind turbine blade coating flat specimens obtained through wind tunnel experiments on the basis of the widely used generalized erosion model. A prediction model that accurately reflects the erosion and wear characteristics of wind turbine blade coatings is constructed using the least squares method. All the function parts included in the model showed favorable fitting effects, and the error between the model prediction results and the measured data was limited to a tolerable range. Therefore, the model has proved to be effective in predicting the erosion rate of wind turbine blade coating materials, which provides a solid theoretical foundation for the numerical simulation of the erosion and wear of wind turbine blades in a two-phase wind-sand flow environment.

Effectiveness of Three Turbulence Modeling Approaches in a Crosswind–Sedan–Dune Computational Fluid Dynamics Framework

The aerodynamic loads of a sedan experience significant fluctuations when passing by a sand dune at the roadside under crosswinds, which can easily cause yawing and overturning. Computational fluid dynamics (CFD) methods, based on different turbulence modeling approaches, yield different aerodynamic results for sedans. This study aims to investigate the effects of three prevailing turbulence modeling approaches (renormalization group (RNG) k-ε, large eddy simulation (LES), and improved delayed detached eddy simulation (IDDES)) on the aerodynamic characteristics of a sedan passing by a sand dune under crosswinds. The CFD dynamic mesh models are constructed using the “mosaic” mesh technique to account for the dune–air–sedan interaction. The reliability of the CFD prediction method is verified by comparing it with field test results. The predictive capabilities of the three turbulence modeling approaches are compared in terms of aerodynamic loads and flow field characteristics. The simulation of sand particle movement is conducted through the discrete phase model, aiming to assess the impact of wind–sand flow on the aerodynamic properties of sedans. Corresponding results show that the aerodynamic loads predicted by the LES model closely match (within 4.4–7.5%) the corresponding data obtained from field tests. While the IDDES and LES models demonstrate similar abilities in characterizing the wind field details, and their results exhibit maximum differences of 8.3–15.7%. Meanwhile, the maximum difference between the results obtained by the RNG k-ε and LES models ranges from 14.8% to 18.4%, attributed to its inability to capture subtle changes in the vortex structure within the flow field. This work will provide a numerical modeling reference for studies on the wind–sand flow and the aerodynamic characteristics of sedans running through the desert, and it has implications for the safe driving of sedans under extreme conditions.

Wind-sand flow simulation and radius optimization of highway embankment under different vertical curve radius

Wind-sand flow simulation and radius optimization of highway embankment under different vertical curve radius

Numerical simulation and field study on predicting wind-blown sand accumulation in sand mitigation measures of the Ganquan railway

The accumulation of sand induced by wind poses a significant challenge to the safety and maintenance of railways in arid and desert regions. Accurate calculation and prediction of sand accumulation are crucial for ensuring continuous railway operation. This research is centered on the region significantly impacted by sand accumulation along the Ganquan Railway. Wind speed, wind direction, and sand carrying capacity data near this section were monitored. Using the collected wind speed, wind direction, and wind-sand flow density data, numerical simulations were conducted using the Computational Fluid Dynamics (CFD) method to predict the amount of sand accumulation within the sand mitigation measures of the Ganquan Railway. Monitoring results indicate that the dominant wind direction in spring and summer is due west, while in autumn and winter it is southwest, with an average wind speed of 12 m/s. A positive correlation was observed between wind-sand flow density and wind speed. The wind-sand flow density above 2 m was nearly zero, indicating that the wind-sand flow structure is concentrated within 2 m from the ground, with an average wind-sand flow density of 3.50×10−5 kg/m3. Through numerical simulation, the characteristics of the wind field and sand accumulation distribution within the calculation domain were determined. A relationship equation between sand accumulation mass and width over time was derived. Initially, the sand accumulation width increases uniformly and then stabilizes, while the sand accumulation mass rises uniformly to a plateau before in-creasing rapidly. From these findings, the optimal period for sand removal was identified as between 350 and 450 days after the sand mitigation measures are put into operation.

Measurement of sand particle motion speed in multiphase wind-sand flow based on piezoelectric ceramic sensors

Abstract Utilizing Pb(ZrTi)O3-5A piezoelectric ceramic (hereafter referred to as PZT-5A) as sensors, we studied the movement speed of sand particles in multiphase wind-sand flows. We developed a mathematical model that effectively links the impact force of sand grains with the output voltage of PZT-5A, incorporating factors such as the piezoelectric coefficient and sand particle characteristics. Additionally, we proposed a new method to accurately determine the elastic recovery coefficient of sand particles using PZT-5A sensor measurements and experimental setups, which is significant for the field of material science. Wind tunnel experiments revealed that at heights ranging from 0.1 to 1.0m, sand particle speeds range from 52.8% to 91.4% of wind speeds. As wind speed increases to 15m/s, sand particle speed nears 91.4% of wind speed. Yet, at a constant wind speed, sand speed drops as sediment discharge rises. This research offers fresh insights into sand particle dynamics in wind-sand contexts.

Numerical simulation and theoretical study on the impact of wind-sand flow of high-speed trains in long tunnel space

When high-speed trains (HST) run in enclosed spaces such as long tunnels, the thermal accumulation of their suspension devices is continuous and cannot be effectively dissipated. In addition, previous experiments or simulations for the heat dissipation of HST in tunnel spaces did not consider the impact of sand. To clarify the impact of HWS-LT on the heat accumulation of HST equipment cabin, this study used the CFD method to numerically simulate the impact of different wind-sand flow concentrations or no-sand wind on the cooling of equipment in the long tunnel space. Firstly, the sand particles in the wind-sand flow gather at the tunnel entrance and enter the equipment cabin with the train as it enters the tunnel. This boundary condition is more in line with actual engineering situations. Secondly, both flows show asymmetric intrusion into the cabin due to the asymmetrical tunnel arrangement, but the sand particles in the wind-sand flow are affected by the vortices and tunnel walls, resulting in more asymmetric flow and some particles being trapped in the grids or filters, leading to outflow ρQ < inflow ρQ. Under the wind-sand flow condition, the temperature of some equipment surfaces shows more significant increases than under the no-sand wind. Finally, contrary to popular perception, the wind-sand flow carrying sand particles can dissipate heat more effectively than no-sand wind, and the higher the volume fraction φ within a certain concentration range, the better the heat dissipation effect. This is because the wind-sand flow has a higher specific heat capacity, which can remove some heat from the contact point between the sand particles and the equipment wall upon contact. The higher sand particle concentration increases the contact frequency and contact area between the sand particles and the equipment wall, and the heat transfer pathway and heat dissipation efficiency are improved.

Wind Tunnel Test of Sand Particle Size Distribution along Height in Blown Sand

In aeolian sand movement, the vertical distribution of sand particle size is intricately linked to sand flux, wind–sand flow field and dune development. In the present study, the distribution characteristics of sand grains in four particle size ranges at nine heights were investigated through sand blowing tests at five different reference wind speeds. The correlation between sand particle size and wind speed indicates that when the particle size was ≥0.35 mm, there was a linear variation of mass percentage with wind speed. When the particle size was &lt;0.35 mm, when Z ≤ 0.15 m, a linear variation of mass percentage with wind speed was found; when Z &gt; 0.15 m, an exponential modification in mass percentage with wind velocity was observed for sand grains falling within this specific range of particle sizes. The correlation between sand particle size and height indicates that when the reference wind speed was ≥15 m/s, the mass percentage of sand particles varied linearly with height. When the reference wind speed was ≤13.5 m/s, the mass percentage of sand grains with particle size in the 0.25–0.35 mm range increases first and then decreases with increasing height. The present results can provide a reference for subsequent research on the aerodynamic characteristics of wind–sand flow fields and on the mechanism of dune formation.

Determine the Optimal Vegetation Type for Soil Wind Erosion Prevention and Control in the Alpine Sandy Land of the Gonghe Basin on the Qinghai Tibet Plateau

There is a dearth of research regarding the windbreak and sand stabilization functions of Caragana liouana shelter forests in the Gonghe Basin of the Qinghai-Tibet Plateau. Therefore, the aim is to elucidate the patterns of near-surface wind–sand activity in artificial Caragana liouana forests of varying ages and mixed forests of different configurations in alpine sandy areas. Additionally, this research seeks to clarify the windbreak and sand fixation effects of these forests. To this end, we have selected artificial forests of Caragana liouana of varying ages (10-year-old pure Caragana liouana forest (10aZJ-C), 17-year-old pure Caragana liouana forest (17aZJ-C), 37-year-old pure Caragana liouana forest (3aZJ-C)) and shrub mixed forests of different mixing modes (10-year-old Caragana liouana and Caragana korshinskii mixed forest (10aNZ-HJ), 10-year-old Caragana liouana and Artemisia desertorum mixed forest (10aSZ-HJ), an 10-year-old Caragana liouana and Salix cheilophila mixed forest (10aWZ-HJ)) within the Sand Control Station of Shazhuyu Village in the Gonghe Basin of the Qinghai-Tibet Plateau as the research subjects. Naked sand dunes were used as the control plot (CK), and through field observations of the wind speed profile, sand transport rate, and micro-topographic changes of each stand plot, we analyzed the wind–sand flow structure characteristics and sand transport process of Caragana liouana of different ages and their mixed forests, eventually proposing suitable afforestation configuration modes for the alpine sand area of the Gonghe Basin in Qinghai. The findings indicate that the wind speed profile within each stand plot follows a linear distribution pattern. Compared to naked dune land, the windbreak effect of each plot decreases as the height from the ground increases. Among them, the 10aWZ-HJ plot significantly alters the wind speed profile and has a substantial windbreak effect; at a height of 200 cm, the windbreak effect can still reach 41.27%. The sand transport rate of each plot fits into an exponential function relationship, with the correlation coefficients (R2) of the fitting equations for each plot all exceeding 0.95 and significantly lower than the control plot, suggesting vegetation can effectively reduce near-surface sand transport. The sand-fixing effects at the height of 0–45 cm from the ground in each plot are as follows: 37aZJ-C &gt; 17aZJ-C &gt; 10aWZ-HJ &gt; 10aNZ-HJ &gt; 10aZJ-C &gt; 10aSZ-HJ. Overall, all plots indicate a state of accumulation. The 10aWZ-HJ plot has the largest relative accumulation area at 88.00%, and the highest average intensity of wind erosion and accumulation at 1.11. Taking into account the stability of the stand and the total protection time, this study suggests that it is suitable to mainly use mixed forests of Salix cheilophila and Caragana liouana in the alpine sand area of the Qinghai-Tibet Plateau. The results of this study can provide a theoretical basis for the construction of windbreak and sand-fixing forests in alpine sand areas.

Aerodynamic impact of wind-sand flow on moving trains in tunnel-embankment transition section: from field testing to CFD modeling

The acceleration of land desertification has led to an increasingly serious threat to the operation safety of tunnel entrance in the Gobi and desert regions by wind-sand flow, and it is urgent to study and enhance the running safety of train. Firstly, an ultrasonic anemometer is used to collect the characteristics of wind-sand flow at a tunnel entrance site in Xinjiang, China. Then, based on the Euler multiphase flow and the SST k-w model, the variation difference law of the train running at the tunnel entrance is revealed under the four inflow conditions of constant crosswind, constant wind-sand flow, pulsating crosswind and pulsating wind-sand flow respectively. Finally, the disturbance law of the solid wind barrier at the tunnel entrance on the wind-sand flow and the influence mechanism on the train’s flow field structure and pressure are revealed. The results show that compared with other cases, the pulsating wind-sand flow has the most significant effect on the moving trains’ aerodynamic loads (ALs), and the sand particles carried in the air cause the trains’ ALs to fluctuate within 9.09%. The solid wind barrier has a significant disturbing effect on the wind-sand flow, and the lightweight sand particles follow the air flow over the top of the wind barrier and are not deposited on the embankment during a short period, and the wind-sand flow’s impact on the HSTs is dramatically reduced. The wind barrier changes the HST’s flow field, and the AL fluctuation of the train is sharply reduced. The maximum values of the head train’s AL coefficients are reduced by 46.53–85.75%.

How do dunes along a desert urban motorway affect the driving safety of sedans? Evidences from long- and short-term monitoring and IDDES

Urban on the edge of deserts usually build motorways in desert areas to fully develop its tourism resources. However, due to the long-term transport effect of wind-sand flow (WSL), the driving safety of sedans might be affected by the erratic dunes next to the desert motorway. Based on this, this study aims to give an idea of how dunes next to desert urban motorways affect the driving safety of sedans. Firstly, the movement law of WSL in desert areas is revealed based on the combination of long- and short-term monitoring methods. After determining the period of strong wind through long-term monitoring, short-term monitoring can be more effective in revealing the movement law of the WSL and the aerodynamic performance of the sedan under the effect of WSL. Afterward, a three-dimensional refined Computational Fluid Dynamics (CFD) dynamic mesh numerical model of WSL-dune-embankment-sedan-air was established based on the mosaic mesh technology. The aerodynamic impact and erosion effects of the WSL on the sedan were investigated. The main results are as follows: 1. Dunes cause varying WSL, with wind speed decreasing to 19–26% on the leeward side and increasing to about 1.35 times at the end. 2. The windward side and front of the sedan experience continuous sand impact, severely eroding the body surface, and posing safety risks. The main contributions of the present study are expected to proposed a cheap simulation scheme based on IDDES (Improved Delayed Detached Eddy Simulation)-DPM (Discrete Phase Model) for WSL-dune-sedan-embankment.

Evolution law of wind-sand flow field of multi-row reed sand barriers and optimal spacing

Evolution law of wind-sand flow field of multi-row reed sand barriers and optimal spacing

Investigating the Mutual Feedback between Wind–Sand Fields and a Running Train on the Bridge–Road Transition Section of a Railway

Strong wind–sand flow exerts great potential safety hazards for high-speed train operations. In this paper, we investigate the aerodynamic characteristics of high-speed trains passing through the bridge–road transition section under a wind-blown sand environment. In particular, we adopt the sliding grid method to simulate the changes in aerodynamic pressure on the train surface when the train passes the bridge transition at different speeds and bridge heights. The variation in the aerodynamic lateral force borne by the vehicle body at various times is then obtained. The results reveal that in the wind–sand environment, when a train drives from the bridge to the embankment, the pressure values on both the windward and leeward sides of the train change abruptly, with the most obvious increase in the lateral force of the head car. Moreover, the abrupt change in pressure increases with the speed of the lateral wind–sand flow. The differential pressure force of the train on the embankment is larger where the differential pressure force on both sides of the head train is the largest. When the train is running in the opposite direction, the differential pressure force on both sides of the train decreases. Compared with the lateral wind condition, the lateral force at different positions of the train under the wind–sand condition exceeds that under the non-sand condition. The average increases in the train body are approximately 17.6% (10 m/s), 10.5% (20 m/s) and 9.5% (30 m/s), which will cause passengers to experience an obvious “shaking” phenomenon.

Interference effect of configuration parameters of vertical sand-obstacles on near-surface sand transport

This study investigates the impacts of height (H) and porosity (P) on the structural properties of wind-driven sand flux in vertical sunflower straw sand-obstacles. We conducted an experiment on sand transport within barriers of various configurations within a 1 m proximity to the surface. In tandem, we monitored wind velocity and direction within the barriers, analyzed total sand transport rate, sand-blocking effects, and cumulative sediment transport rate heights for various parameter configurations, and devised a best sand transport flux model for use within the sand-obstacle. The efficacy of vertical sunflower stalk sand-obstacles in mitigating sand movement has been demonstrated to fall within the range of 37.26%–92.31%. This study reveals a significant correlation between barrier height and porosity in achieving this effect (p &amp;lt; 0.05). High and densely configured sand-obstacles lead to an accumulation of intercepted sand material in front of the front row of the sand-obstacle. In contrast, low and sparsely arranged sand-obstacles exhibit a delayed state of sand material accumulation. Furthermore, with an increase in the height of the obstacle and a decrease in porosity, there is a diminishing trend in the sand transport rate within the obstacle. Concurrently, the height of sand transport within the barrier exhibits an upward trend. A three-parameter exponential function has been employed to more precisely simulate the wind-sand flow structure characteristics within a 1-m height range of the barrier. These research findings contribute to an enhanced understanding of the impact of different vertical sand-obstacle configurations on near-surface wind-driven sand transport patterns in active desert areas. Moreover, they furnish both theoretical underpinnings and practical guidance for the scientific configuration of vertical sand-obstacles.

Comparison of jack bean and soybean crude ureases on surface stabilization of desert sand via enzyme-induced carbonate precipitation

Enzyme-induced carbonate precipitation (EICP) is a prominent biogeotechnical technique for soil stabilization to address desert invasion and dust emission issues. This study investigates the bio-cementation efficacy of EICP mediated by jack bean crude urease (JCU) and soybean crude urease (SCU) on surface stabilization of aeolian sand from Tengger Desert. Topsoil properties of the EICP-treated sand including CaCO3, organic matter content, surface strength, and wind erosion resistance were evaluated. The urease activity of JCU was 3.4 times higher than SCU, resulting in a higher CaCO3 content and surface strength of JCU-treated topsoil. The optimum bean dosages were observed at 40 g/L jack bean and 80 g/L soybean for achieving maximum CaCO3 content and surface strength, respectively. EICP-treatments with excessive bean dosages would decrease the surface strength due to the interference of organic matter precipitation on effective bridging between the generated CaCO3 crystals and the sand particles. Wind erosion resistance was evaluated under wind-sand flow condition at a wind speed of 13.8 m/s, which was positively correlated with surface strength. JCU presented an overall greater stabilization potential of topsoil than SCU. Additionally, the urease costs of EICP-treatments with JCU and SCU were reduced by about 380–1400 times compared with commercially available ureases.

Numerical simulation on wind-sand flow field around railway embankment with different wind angles

The intersection angles of the railway trend and wind direction are different in practical engineering, resulting in different sand hazard intensities. This research explores the characteristics of the wind-sand flow field, wind speed change, and sand accumulation near railway embankments with different wind angles to reveal the formation mechanism of sand hazards. A numerical simulation of the wind-sand flow field around embankments under wind angles of 15°, 30°, 45°, 60°, 75°, and 90° with different friction wind speeds is conducted on the basis of the Euler two-phase flow model; moreover, the variation law of wind speed and the characteristics of sand accumulation distribution near the railway are discussed. Results indicate that when the wind-sand flow moves to the embankment, it is obstructed and forms different velocity zones. The deceleration zone on both sides of the embankment and the acceleration zone above the embankment increase remarkably with the increase in wind angle. When the friction wind speed is constant, the greater the wind angle, the greater the variation of wind speed near the surface around the embankment, which is more evident on the leeward side of the embankment. The sand accumulation amount on both sides increases with the increase in the wind angle. Under a wind angle of 30°, almost no sand accumulated on the leeward side slope. With the increase in friction wind velocity, the sand accumulation amount on the windward side of the other embankment decreased except for the embankment with a wind angle of 90°, and that on the leeward side of the other embankments decreased except for the embankment with a wind angle of 15°. These results provide a theoretical basis for the route survey and design of the railways in blown sand areas and the optimization of prevention and control measures.

SPH numerical simulation study on wind-sand flow structure of multi-diameter sand

SPH numerical simulation study on wind-sand flow structure of multi-diameter sand

Study on Sand-Accumulation Changes of Highway and Formation Mechanism of Sand Damage in Drifting Dunes Areas

After the construction of desert highway, the physiognomy changes caused by surface wind erosion and accumulation not only seriously threaten the stability of road structure, but also have a tremendous impact on the safety of the highway operation and the maintenance work on the highway. The purpose of this paper is to explore the change of sand sedimentation and the law of sand transport along the highway in the moving dune areas, and to clarify the change of sand flow and the formation mechanism of sand damage in the moving dune areas. Taking the test section of Wuhai-Maqin Expressway in the hinterland of Tengger Desert as the research object, the on-site observation of sand accumulation and the recording of wind information by small weather stations were adopted, supplemented by CFD numerical simulation method, in order to provide reference for the construction of sand control system in moving dune areas. The study results show that: (1) Dunes not only obstruct wind-drift sand but are also the sediment source condition for forming road sand. The windward dunes near the road are affected by wind and the deposition of sand will quickly bury the road in the strong wind season. (2) Compared with highways with flat terrain, the existence of dunes affects the flow field structure and the distribution of sand sedimentation on the highway, in which, under the influence of the gathering effect, the flow velocity reaches the maximum at the top of the dune and a large low-speed recirculation zone is formed on the lee side of the dune, easily causing sand accumulation. (3) Sediment accumulates at the windward side of the embankment or dune where sandy air current is easy to saturate. However, with the increase of wind speed, in addition to the grit carried by the sandy air current itself, new sand rolled up on the windward side of the dunes also form deposits on the road surface and the amount of sand-accumulation on highway surface and leeward side tends to increase. As a result, for the highway in drifting sand dunes areas, sediment prevention and control measures should be taken actively. It is necessary to remove sediment from the road in time and reduce the moving speed of sand dunes and the deposition range of wind-sand flow, ultimately for the purpose of reducing the damage wind-sand activity causes to the highway in desert.