A 3-dimensional simulation of mixed sand transport

A combined computational fluid dynamics and discrete particle method approach was proposed to perform numerical simulation on a mixed sand transport. In this paper the volume averaged Navier-stokes equations were solved to calculate the gas motion, taking into account the interaction between gas and particles; the particle motion was calculated using Newton's equation of motion, where a hard sphere model was used to describe the particle-particle and particle-wall collisions. In this model, the motion of individual particle was three-dimensional and the flow of continuous gas was two-dimensional. The results showed that, the total sand mass flux decreased exponentially with height above 2 cm and deviated below 2 cm. The distributions of mass flux of each size group were very different from each other. For the large size group, the sand mass flux decreased exponentially with height, while the sand mass flux increased with height firstly and then decreased for the other size groups. The particle mean horizontal velocity of all sand groups increased logarithmically with height and decreased with particle size at the same height above 1 cm, but contrary result appeared below 1 cm. The mean particle size decreased linearly with height above 2 cm and deviated blow 2 cm.