Open-source modelling of aerosol dynamics and computational fluid dynamics: Nodal method for nucleation, coagulation, and surface growth

Understanding formation, growth and transport of aerosols is critical to processes ranging from cloud formation to disease transmission. In this work, a numerical algorithm of aerosol dynamics including nucleation, coagulation, and surface growth was coupled with flow and heat transfer equations enabling the solution of three-dimensional multi-physics aerosol processes in an open-source platform. The general dynamic equation was solved by a nodal method where the particle size distribution was represented by a finite number of nodes. The models were verified by comparing four test cases, (1) pure coagulation, (2) nucleation and coagulation, (3) pure surface growth, and (4) a general dynamic equation that includes the three mechanisms provided in literature. A high temperature aerosol flow in a cooled pipe is chosen as a tutorial case of coupled computational aerosol and fluid dynamics. The aerosolGDEFoam code is available at https://openaerosol.sourceforge.io and can be further modified under GNU general public licence.厘清气溶胶（aerosol）的形成、生长与输运机制，对于从云团生成到疾病传播的诸多过程均具有关键意义。本研究将包含成核、凝并与表面生长过程的气溶胶动力学（aerosol dynamics）数值算法，与流动及传热方程进行耦合，从而可在开源平台上求解三维多物理场气溶胶过程。本研究采用节点法求解通用动力学方程（general dynamic equation），通过有限数量的节点表征颗粒物粒径分布。通过对比四个标准测试算例对模型进行验证：(1) 纯凝并过程；(2) 成核与凝并耦合过程；(3) 纯表面生长过程；(4) 涵盖上述三种机制的文献基准通用动力学方程场景。本研究选取冷却管道内的高温气溶胶流动场景，作为计算气溶胶与流体动力学耦合的教学演示算例。aerosolGDEFoam代码可从https://openaerosol.sourceforge.io 获取，并可在GNU通用公共许可证（GNU General Public Licence）条款下进行二次修改。