黏性泥沙絮凝-沉降-再悬浮运动过程数学模型研究

黏性泥沙运动特性是河流海洋泥沙动力学研究热点之一。为研究紊动水体中黏性泥沙运动过程及其机理,以絮凝动力学方程为基础,通过设置不同粒径级别的泥沙絮团再悬浮量为下边界条件来反映黏性泥沙絮团的再悬浮,建立了黏性泥沙絮凝-沉降-再悬浮动态过程数学模型。模型验证结果表明,新建模型可用于描述黏性泥沙絮凝-沉降-再悬浮运动过程,且具有一定的精度。最后以泥沙絮团体积分布为指标,探讨了强紊动水体中絮凝、沉降和紊动扩散在这一动态过程中的作用。研究结果表明,强紊动水体中,上层区域泥沙絮团分布的决定因素是沉降和紊动扩散;中部区域是絮凝;下层区域是絮凝和紊动扩散。

A model for the flocculation-settling-resuspension process of cohesive sediment

The motion characteristic of cohesive sediment is an important research subject. In order to study the movement of cohesive sediment and its mechanism,this paper presents a model to simulate the flocculation-settling-resuspension process of cohesive sediment by taking the resuspension amount of sedi-ment floc with different sizes as the lower boundary condition, based on flocculation kinetic equation. The model was checked through comparing simulation results with published experiment data. The verification re-sults show that the proposed model can be used to simulate the flocculation-settling-resuspension process of cohesive sediment, and has certain accuracy. Finally, the paper used the volume distribution of sedi-ment floc as an index to discuss the function of flocculation, settling and turbulent diffusion through the proposed model. The result shows that, in strong turbulent flow, the settling and turbulent diffusion deter-mine the distribution of sediment floc in upper zone, the flocculation in middle zone, while the floccula-tion and turbulent diffusion in lower zone.