Polimeno Matteo, Kim Changho, Blanchette François
Department of Applied Mathematics, University of California, Merced, California95343, United States.
ACS Omega. 2022 Oct 31;7(45):40826-40835. doi: 10.1021/acsomega.2c03547. eCollection 2022 Nov 15.
In this Brownian dynamics simulation study on the formation of aggregates made of spherical particles, we build on the well-established diffusion-limited cluster aggregation (DLCA) model. We include rotational effects, allow diffusivities to be size-dependent as is physically relevant, and incorporate settling under gravity. We numerically characterize the growth dynamics of aggregates and find that their radius of gyration, , grows approximately as ∼ for classical DLCA but slows to an approximate growth rate of ∼ when diffusivity is size-dependent. We also analyze the fractal structure of the resulting aggregates and find that their fractal dimension, , decreases from ≈ 1.8 for classical DLCA to ≈ 1.7 when size-dependent rotational diffusion is included. The addition of settling effects further reduces the fractal dimension observed to ≈ 1.6 and appears to result in aggregates with a vertical extent marginally smaller than their horizontal extent.
在这项关于由球形颗粒形成聚集体的布朗动力学模拟研究中，我们基于成熟的扩散限制凝聚（DLCA）模型展开。我们纳入了旋转效应，允许扩散率如实际情况那样依赖于尺寸，并考虑了重力作用下的沉降。我们通过数值方法刻画了聚集体的生长动力学，发现对于经典的DLCA，其回转半径(R_g)大约以(R_g\sim t^{1/2})的方式增长，但当扩散率依赖于尺寸时，其增长速度减缓至大约(R_g\sim t^{1/3})。我们还分析了所得聚集体的分形结构，发现其分形维数(D_f)从经典DLCA时的约(1.8)降至包含尺寸依赖旋转扩散时的约(1.7)。沉降效应的加入进一步将观测到的分形维数降低至约(1.6)，并且似乎导致聚集体的垂直范围略小于其水平范围。
