Research On The Numerical Imitation Of Sand Ripple Formation And The SPH Method

At present, many persons have all become aware of the degeneracy of desert encroachment as well as environment brings people's life many sorts of harms. These harms are by no means a regional or a country' s problem; instead they are a global problem. This paper primarily includes several aspects' work as followings: (1) Study and investigate those research fruits on the mechanics of wind-blown sand flowing what the domestic and foreign scholars researchers acquired. These research fruits include sand particles'starting, suspension, salutation and surface creep, sandstorm current structure, sand ripple motion and so on .We have made the spot wind tunnel experiments in the brim of northwest Mountain Takalamagan, acquire the typical sand ripple shape and can conclude the comparatively ideal sand— defending wall according to the sandstorm current structure in front of the sand— defending wall and the sand ripple shape. (2). Have made the numerical imitation of sand ripple shaping using the theories of the stream field and desert flow field, which is made full of comparing to the previous numerical imitation method on the relation of the stream field and desert flow field. The final emulation result matches the natural state very much. We also discuss the effect of the following conditions on the computational results as followings: (1) the formula of the sand transfers, (2) boundary condition on the sand surface, (3) computational grid and (4) time increment to calculate the sand movement. (3) Have researched on the numerical imitation method of the Smoothed Particle Hydrodynamics(SPH), summarized the theoretical foundation on SPH method systematically and imitate several real examples using the SPH program. Finally the dynamic outcomes that consist with the real instance were obtained. (4) The objective of this research is to apply a new numerical imitation method (SPH) to the sand movement calculation and to IIpredict these phenomena with high accuracy. It is very difficult to predict the shift of the sand dunes by means of observations or experiments methods because of the large spatial scale of the dune and the long time scale of the movement. On the other hand, numerical methods seem to be very powerful to investigate these phenomena owing to the recent development of the high-speed computer. But due to my limited level and fastened time, I haven't applied this SPH method to the simulation of the sand ripple forms. However, it will continue to be finished in my subsequent research.