Lattice Boltzmann Simulation Of Velocity Profiles Of Saltating Sand Particles And Numerical Prediction On Erosion Damage Caused By It

The motions of sand particles driven by wind are very important physical processes, which include ejection, saltation, and sedimentation. The wind-sand flow develops when the number of moving particles becomes large. The wind-sand flow can result in several serious environmental problems, such as the land degradation, decline of the air quality and so on. Researches on the velocity of sand particles have drawn much attention, as the velocity of sand is crucial to the energy flux and mass flux of the wind-sand flow, which are indexes of the intension of flow. The structures and equipments near surface suffer serious erosion damage caused by blown sand, particularly when the particle number is large and velocity is big. Consequently, study about the velocity and the erosive ability of sand particles are quite essential.In the first part, the Lattice Boltzmann Method is used in calculating the two dimensional wind-sand flow near the bed suiface, to reach the conclusion about the mean velocity profiles of sand particles. Firstly, the simulations are carried out in the conditions of flat bed surface and single porous wind fence; comparisons of simulated results with those experimental results obtained by other researchers are made. Secondly, the conditions of two porous wind fences are calculated. The different span and geometric porosity of the porous wind fence are considered. Then the different effects of wind fence on shelter of saltating sand particles are shown. The result verifies the conclusion that the mean velocity profiles of sand particles can be fitted by the Exponential function, which is reached by other researchers. The simulated results also show that the wind speed and the velocity of sand particles are obviously weakened because of the existence of the fence; if there are several wind fences, the effects on shelter of saltating particles become weaker as the span and porosity bigger.In the second part, the erosion of representative material Inconel718caused by wind-blown sand in the natural environment was numerically simulated. The erosive abilities of sand particles in different environmental conditions (e.g. height, wind velocity) were quantitatively investigated. A saltation-erosion model was set up based on the introduction of the model describing the saltation of sand particles in the coupled wind-sand-electricity fields. The computational result show that, the erosion caused by windblown sand usually occurs near the bed surface. The quantity of erosion shows stratification pattern as well as the mass flux of the sand flow. The higher velocity of wind is, the faster the erosion. The erosion rate increases first and then decreases with the increasing of the saltating distance. Small sand particles have greater erosive capacity than the lager particles in the same wind field.