Influence of film coefficient during multicomponent diffusion – KCl/NaCl in biosolid for static and agitated system using 3D computational simulation

Abstract The influence of film coefficient formed during the diffusion of inorganic salts (NaCl and KCl) in biosolids was studied using a 3D computer modeling by Finite Elements Method (FEM) in COMSOL Multiphysics® software combined with SOM-type Artificial Neural Networks (ANN). Such tools have shown that the influence of the film formed in the biosolid/solution interface occurs in a heterogeneous manner and is due to the matrix geometry, the type of system (agitated or static) and the ion size (Na+ or K+). The influence of film coefficient was more pronounced for K+ ion, and for a static system. Comparing the geometry of biosolids, ion diffusion was more pronounced in the (Y±) axis in relation to other axes, X (±) and Z (±), as well as in between the poles (±) of this axis. FEM simulation associated with SOM-type ANN were efficient tools to evaluate this complex and unknown biophysical phenomenon.摘要 本研究借助COMSOL Multiphysics®软件，采用有限元法（Finite Elements Method, FEM）结合自组织映射型人工神经网络（SOM-type Artificial Neural Networks, ANN）开展三维计算机建模，探究了无机盐（氯化钠NaCl、氯化钾KCl）在生物固体中扩散过程中形成的膜系数的影响规律。研究结果表明，生物固体/溶液界面处形成的膜的影响呈现非均质性，该效应源于基质几何结构、体系类型（搅拌或静态）以及离子尺寸（Na+或K+）。膜系数对K+离子以及静态体系的影响更为显著。对比生物固体的几何构型，离子扩散在Y(±)轴上相较于X(±)轴与Z(±)轴更为明显，且集中于该轴的两极(±)之间。有限元模拟与自组织映射型人工神经网络的联用方案，是评估这一复杂且尚未完全明晰的生物物理现象的高效工具。