三维混合沙输运数值模拟

采用计算流体力学和颗粒离散元耦合的方法模拟了三维混合沙输运过程。采用体平均的Navier—stokes方程来描述气相运动,考虑了气相和颗粒相的相互作用。颗粒运动通过求解牛顿运动方程来求解,采用硬球模型描述颗粒和颗粒及颗粒和壁面的碰撞。本模型中,颗粒运动是三维的而气相运动是二维的。计算结果表明：总输沙率沿高度方向在大于2cm以上按照指数衰减,在2cm以下则偏大;各粒径颗粒具有不同的输沙率分布,粗粒径颗粒按指数规律衰减,其它粒径颗粒输沙率随高度先指数增加后减少;各粒径颗粒平均水平速度随高度对数函数增加且同高度时随粒径增大而减小,1cm高度以下则相反;沙粒平均粒径沿高度线性递减,2cm以下粒径偏大。

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.