电离作用下黏性细颗粒泥沙絮凝沉降数值模拟

Numerical simulation of flocculation-settling of cohesive fine sediment with ionization

基于分形理论构建泥沙颗粒的絮凝沉降模型,从三维角度动态模拟絮团在布朗运动、颗粒静电力和重力作用下的发育、沉降过程.研究结果表明:絮团形态与泥沙颗粒的表面电荷量有关,电荷量越大,絮团形态越开放;不同带电量泥沙颗粒的絮凝速度与沉降速度具有差异性,表面电荷量越大絮凝沉降速度越缓慢;泥沙颗粒的带电量对絮团平均粒径分布有显著影响,不同带电量下絮团达到最大直径所需时间不同.研究成果进一步揭示了天然河流中黏性细颗粒泥沙絮凝现象的内在机理.

A three-dimensional model base on fractal theory was employed to simulate the formation and development of floccule in cohesive fine sediment due to Brownian movement,gravity and electrostatic force.The results show that the floccules morphology is related to electric charge of particles which form these floccules,in detail,more charge in particles results in opener floccules morphology.Moreover,the sedimentation of particles is associated with their electric charge,specifically more charge cause lower flocculation-sedimentation velocity.In addition,the floccules diameter is affected by the particle charge,and the diameter distribution tends to be uniform with increasing charge,however,it spends more time to get the maximum diameter.These findings succeed to reveal the mechanism of flocculation for cohesive fine sediment in natural rivers.