Numerical Study On Sand Morphology Forming Process Under Non-Uniform And Un-Steady Steam Flow

Sand morphology process is the Earth’s surface topography, especially the most common in arid areas. Aeolian ripple is formed the most basic surface topography type under wind power, and its evolution with movement characteristics of flow field and the sand surface substances’ composition is closely related. Ripple with regular geometric patterns generally manifests a gentle ascent windward and a rapid ascent leeward, but because of kinds of variances under the natural conditions, its shape is not uniform. Due to the interaction of airflow and Sand group , the external shape and internal structure of the ripple has become complex and diverse. Therefore, the ripple is directly embodiment of the interaction of the steam flow field and sand flow field, but also it is the major manifestations of sand appearance.Traditionally, based on the conclusions got by wind tunnel observation outdoors or experiment, using some formula to describe the flow field and bed deformation, and bed height, transporting sand rate and other parameters as continuous variables, the ripple formation and evolution can be revealed by simple solution. With the development of computer technology, numerical simulation study has gradually become an important means of wind patterning ripple formation mechanism. From the field and wind tunnel experimental data or theoretical analysis results, the suffered forces of the sand are analyzed, and the equations of motion of sand are established. On the basis, numerical simulation was carried on. By compared calculated results with experimental data, we determine the analysis which the sand suffered is correct or not, and the simplification of numerical simulation and the determination of boundary conditions is suitable or not.In this paper, in order to study the problem of desertification caused by the wind flow, from the point of view of dynamics, the basic research of the wind and sand two-phase flow field was carried on and the constitutive relation formula of the wind flow was derived. Take wind-sand flow field as the object of study, from the mechanical point of gas-solid flow view, the actual nature of the wind-sand flow field was analyzed. From the actual nature of the wind-sand flow field, firstly, it elaborated on the establishment of constitutive equations and the process of discrete solution, and then analyzed the involved relationship and independence of the steam flow field and sand flow field, and elaborated on the building process of the constitutive formula of the sand flow field, and gave the mathematical model of the sand flow field under the steam flow field influent. Finally, the sand flow field’s model under the steam flow field’s influence was carried out the discrete processing, and simulated the sand morphology forming process in fixed, semi-fixed and free sand flow field under the uniform and non-uniform steam flow field and the sand flow field in different boundary conditions by, and its numerical simulation results and field experimental results are analyzed and compared.