The Numerical Simulation Of Sand-flow In Steady And Unsteady Inflow

The sand-flow, as the typical represents of gas-solid two-phase flow, the mecro- and macro-influence of turbulence on it are not negligible. Conversely, thorough analysis on how to effecting the turbulence by the movement of many particles in sand-flow is very necessary.In addition, the saturation length has close relation with the experiment and the minimal dune and the wavelength of dunes. However, they are very deficiency on the above mentioned questions. Therefore, using the sand-flow model of combining the Large Eddy Simulation (LES) for the N-S equation and the Particle trajectory Model for particles movement, accurately simulation to no-sand wind flow as the basis and premise, this paper simulate and analysis on the sand-flow in steady and unsteady inflow, then deep study on the sand particles effecting the average and instantaneous characteristics of wind field. The main contents are introduced as follows as:1,First, we simulate the no-sand wind field in steady and unsteady inflow, consistent with the observation results, then simulate the two-dimension barchan dune wind field in steady inflow, obtain the Reynolds stress and shear stress distribution along slope and the quantitative analysis of the shedding vortex from slope top.2,We solve the N-S of contained sand and the sand particles movement equations, combining the splashing function which describe the sand particles collision to sand bed. After discussion on the sensitivities of program to mesh and domain of simulation, compare the one-dimension characteristics with the existing results, proof that the program is correct and reliable. Then, we study on evaluation of sand-flow and some non-uniform characteristics, the saturation length and time changed with the inflow, etc.3,Based the observation data at the height 2m, generate the inflow boundary conditions and simulate the sand-flow in nature wind field. From the view of mecro (the sand particles average speed and the response time) and the macro (the mass flux and the sand-flow height), discussed the influence of turbulence on sand-flow and the two-dimension characteristics of nature sand-flow. Finally, we study the sand particles group movement how to effecting the average (the profile of wind) and turbulence (intensity and kinetic energy) characteristics.