絮体破碎再形成行为的计算机模拟

为了深入探讨絮体破碎行为对其分形成长及结构的影响,借助一种简化的絮体破碎模式对絮体破碎/再形成过程进行计算机模拟。通过对比分析破碎前后虚拟絮体的形态特征及其统计特性,得出如下主要结论：（1）絮体发生破碎后,所形成碎片的形态特征直接影响着再形成絮体的形态及恢复程度;（2）絮体外围枝杈结构的破坏,有利于运动粒子进入絮体内部或者均匀地排列在凝聚核周围,改善絮体质心附近颗粒的空间分布,从而有效地提高其致密性和抗剪切破坏能力;（3）在絮体分形成长过程中,存在一个使其由各向同性向各向异性过渡的临界状态,之后发育良好的枝杈对其余枝杈生长的抑制作用增强。此外,在实际操作时还应严格控制絮凝体系的物化条件,不宜使絮体过度破碎,以获得较好的絮凝效果。

Computer simulation of floc breakage and regrowth behaviors

In order to deeply explore the impact of floc breakage behavior on its fractal growth and structure,floc breakage and subsequent regrowth processes were simulated by computer based on a simplified mode of floc breakage.Through comparative analysis of morphological characteristics and statistical properties of virtual flocs before and after breakage,the main conclusions were as follows：（1） morphological characteristics of floc fragments formed after breakage have a direct effect on the morphology and recovery degree of reformed flocs;（2） breaking the surrounding branch structures of flocs benefits moving particles to enter into floc interior or be uniformly arranged around the aggregating core,modifying the spatial distribution of particles in the vicinity of aggregate mass center,and thus improving floc compactness and the ability to resist shear damage;（3） there is a critical state for a transition from isotropic to anisotropic during floc fractal growth,and then the inhibition of well-developed branches become intense to others.Additionally,for better flocculation effect,the physio-chemical conditions for flocculation system should be strictly controlled in an operational sense to prevent floc overbreakage.