用双流体颗粒-壁面碰撞模型模拟混合层流动

将考虑壁面粗糙度的双流体颗粒-壁面碰撞模型加入到二阶矩两相湍流模型中,模拟了平面混合层两相流动.结果表明,考虑壁面粗糙度的模型的模拟结果与不考虑的结果相比,给出的纵向平均速度更小、纵向脉动速度更大,与实验值更接近.对于大颗粒,这种影响尤其明显.这些趋势与颗粒轨道模型的模拟结果定性上一致.这表明,窄通道内大颗粒和壁面的碰撞对颗粒流动特性有更显著的影响.

Simulation of mixing-layer gas-particle flows using a two-fluid particle-wall collision model

A two-fluid particle-wall collision model is proposed. It takes into account the effects of the friction, restitution and in particular the wall roughness, and hence the redistribution of Reynolds stress in different directions, the absorption of turbulent energy from the mean motion and the attenuation of particle motion by the wall. The proposed model is incorporated into the second-order moment two-phase turbulence model to simulate mixing-layer gas-particle flows. The results show that the two-fluid particle-wall collision model accounting for wall roughness gives smaller longitudinal mean velocity and greater longitudinal fluctuation velocity than those obtained using the model not accounting for the wall roughness. This is in good agreement with the experimental results. These results are also in qualitative agreement with the simulation results given by the particle trajectory model. For large particles, such effect is more evident. The results point out that in narrow channels the particle-wall collision has more obvious effect on the particle flow behavior.