粘性细颗粒泥沙淤积过程自组织及成团起动机理研究

Five main issues are explored to investigate the self-organization in the aggregation-sedimentation process of the cohesive fine particles and the incipient motion of the floc on the riverbed. 1. Based upon theories on electrical double layer and the colloidal stability, the cohesion mechanism of fine particles was researched, and the method for the estimation of water film thickness was developed. Further, series of experiments were carried out to study the influences of concentrations of the sediment and electrolyte, the valence of cation, and PH value on the flocculation. 2. Five kinds of micro-photographics were used to observe the morphological structures of the floc, and then the fractal dimension of the floc was calculated from the digital photo images obtained using Box-counting arithmetic. 3. Modified Smoluchowski equations that describe the kinetics of the particle aggregation incorporating breaking up of flocs were proposed, and then were numerically integrated using the third order Runge-Kutta method. 4. Minimum total potential energy assumption was demonstrated both in theoretic way and in experimental way, and some experimental evidence was gained to support the assumption. 5. With the concept of the fractal and random structure of the floc during the deposition, a model of DLCA was simulated to find the mechanism of the floc in incipient motion under the turbulence flow.

粘性细颗粒泥沙淤积物的成团起动现象和缺陷发生-缺陷扩展-局部崩溃的冲刷过程是现有起动理论尚不能解释的现象，也是河道、水库、港口、航道冲淤计算需要解决的实际问题。本课题拟从统一的自组织角度，研究淤积物细观结构和分形生长模型，以及床面缺损与紊动交互作用机制。建立成团起动判别条件和缺陷发生-缺陷扩展-局部崩溃的可视化模拟方法。..