反应概率置限二维DLCA模型分形模拟

本文采用有限扩散集团凝聚(Diffusion-Limited Cluster-Cluster Aggregation,DLCA)模型,编写反应概率置限二维DLCA模型程序,模拟絮凝体分形生长过程,计算其分形维数和空隙率等参数,探究在反应概率各向同性及各向异性条件下不同反应概率对絮凝体分形模拟结果的影响。在反应概率控制下的分形模拟更加符合实际絮凝体的生长过程,该模拟方法对探究絮凝体的生长机理及提高沉降分离效率有重要的理论指导价值。模拟结果表明:反应概率对絮凝体的形态及分形特征影响较大,反应概率越小,絮凝体团簇尺寸越小,团簇数目越多,团簇分布越稀疏,表现为空隙率增大,分形维数减小;反应概率越大,絮凝体团簇尺寸越大,团簇数目越少,团簇分布越密集,表现为空隙率减小,分形维数增大;反应概率各向异性直接影响絮凝体的形貌,絮凝体会偏向反应概率较大的方向聚集生长,絮凝体团簇形状十分细长,团簇数目较少,团簇分布较密集,但偏向不同方向生长絮凝体的分形维数相差不大,是同一性质的分形。

Simulation on flocs growth using two-dimensional reaction-limited DLCA model

Based on Diffusion-Limited Cluster-Cluster Aggregation(DLCA),a two-dimensional flocs growth was simulated by the reaction-limited DLCA model program.Parameters such as fractal dimensions and porosity were calculated,in order to study the influence of isotropic and anisotropic reaction probability on the results of the simulation of flocs growth.The simulation of flocs growth limited by reaction probability matched the practical process of flocs growth quite well,which was a valuable theory on studying the mechanism of flocs growth and boosting the efficiency of settlement and separation.The simulation results revealed that the reaction probability had a relatively evident impact on the fractal characteristic and appearance of the flocs.The smaller the reaction probability,the smaller the size of clusters,the bigger the amount of clusters,the more sparse the distribution of clusters,which were characterized by the decrease of fractal dimension and the increase of porosity.The bigger the reaction probability,the bigger the size of clusters,the less the amount of clusters,the more dense the distribution of clusters,which were characterized by the increase of fractal dimension and the decrease of porosity.The flocs morphology was affected directly by the anisotropy of reaction probability,it would obviously grow towards the direction whose reaction probability was bigger,the figure of flocs was pretty slender,the amount of clusters was less,the distribution of clusters was much denser,however,the fractal dimensions of flocs which grew towards different directions were much the same,which were of the same nature.