紊流对粘性细颗粒泥沙絮凝影响  

Effect of turbulent flow on flocculation of fine cohesive sediment

作　　者：柴朝晖[1] 杨国录[1] 王茜[2] 余明辉[1] 

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室污淤泥研究中心,湖北武汉430072 [2]长江科学院,湖北武汉430010

出　　处：《水科学进展》2012年第6期808-814,共7页Advances in Water Science

基　　金：国家重点基础研究发展计划(973)资助项目(2011CB403300);中央高校基本科研业务费专项资金资助项目(2012206020202)~~

摘　　要：以分形聚集生长模型为基础,通过三维模拟泥沙颗粒在布朗运动、重力沉降和紊流作用下的碰撞、粘结和破碎过程,探讨了紊流对粘性细颗粒泥沙絮凝速度、絮团平均粒径及分形维数的时空影响。试验结果表明:紊流作用下,泥沙絮凝及絮团平均粒径的变化可分为加速段、等速段和减速段,絮凝等速段的作用时间及粒径等速增长段的速度均随紊动强度呈先增后减的规律,且中部区域的絮凝速度和絮团平均粒径较小;泥沙絮团分形维数随水流紊动强度的增加逐渐增大,最终趋于稳定,随时间呈先减后增的规律。模拟空间下部区域分形维数最大,上部次之,中部最小。Using the fractal cluster growing model, the effect of turbulent flow on the flocculation velocity, the aver- age diameter and the fractal dimension of floes are studied. The model simulates the collision, the bonding and break- age of sediment particles under the action of Brown motion, gravity settling and turbulent flow in a three-dimensional space. The resuhs show that the process of flocculation and average diameter of floes can be divided into three stages ： accelerating section, uniform section and descending section. The flocculation duration of uniform section appears to be first increasing then decreasing as the turbulent intensity increased, and so do the growth of average diameter. Mo- reover, the flocculation velocity and the floes average diameter are smallest in the central region. The fractal dimen- sion of floes increases with the turbulent intensity increasing, and is finally stabilized. Besides, the fractal dimension of floes appears to be first increasing then decreasing with time. The fractal dimension of floc is largest in the lower re- gion, followed by the upper region, and the lowest value is found in the middle region.

关 键 词：粘性细颗粒泥沙 絮凝 紊流 雷诺数 时空变化 

分 类 号：TV143.1[水利工程—水力学及河流动力学]