基于湍流猝发的明渠流悬沙浓度分布

泥沙悬浮是湍流猝发直接作用的结果．本文基于这一力学机理，利用湍流猝发平均持续时间和猝发强度构造明渠流悬沙湍流扩散模式．模式涉及的唯一参数线性地随悬沙沉降速度对摩阻流速的比值增大而增大，表征较粗、较重的泥沙颗粒的悬浮需要具有更多能量、持续时间更长的湍流猝发作用与之相适应，物理意义明确．经水槽实验资料验证，本模式可精确模拟悬沙浓度沿垂线的分布．对类似流动中其它异质污染物的湍流扩散。

Suspension of sediment particles is closely associated with the bursting process in wall turbulent flows. Based on this mechanism, a new turbulent diffusion model for suspended sediment in open channel flows is formulated by using the mean duration of bursts and the bursting intensity. The only coefficient involved in the model increases linearly with the ratio of the particle's setting velocity to the friction velocity ,indicating that more energetic turbulent bursts with longer durations are required for the suspension of coarser and heavier particles. The developed model is shown to exhibit excellent performance for the modeling of sediment concentration distributions.