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. Programme summary: Programme title: aerosolGDEFoam CPC Library link to programme files: http://dx.doi.org/10.17632/3s368jpdx2.1 Developer's repository link: https://openaerosol.sourceforge.io/ Licencing provisions: GNU General Public Licence 3 Programming language: C++ Nature of problem: aerosolGDEFoam solves the general dynamic equation coupled with flow and heat transfer equations enabling the solution of three-dimensional multi-physics aerosol processes using the open-source computational platform, OpenFOAM [1]. The general dynamic equation describes changes in aerosols due to e.g. nucleation, coagulation and evaporation/condensation, processes which depend on local conditions such as temperature and humidity. A zero-dimensional form of the general dynamic equation from Prakash et al. [2] has been implemented and verified with previously published examples. Solution method: aerosolGDEFoam employs an explicit time-stepping for the time-dependent source terms for aerosol dynamics. The solution methods and schemes provided by OpenFOAM 6 are used for spatial derivatives. References: [1] OpenFOAM6, OpenFOAM v6, in The OpenFOAM Foundation, https://openfoam.org/, [2] Prakash, A., A.P. Bapat, and M.R. Zachariah, A Simple Numerical Algorithm and Software for Solution of Nucleation, Surface Growth, and Coagulation Problems. Aerosol Science and Technology, 2003. 37(11): p. 892–898.