Dry deposition model for a microscale aerosol dispersion solver based on the moment method

TL;DR

This paper introduces a dry deposition model integrated into a moment method solver within OpenFOAM, accurately simulating aerosol dispersion and deposition around vegetation with significant computational efficiency gains.

Contribution

The paper develops a novel dry deposition model for the moment method, including five key processes, and demonstrates its effectiveness and efficiency in microscale aerosol dispersion simulations.

Findings

The model accurately reproduces particle size distribution shapes.

Relative difference in third moment is below 10%.

Eightfold computational speedup over sectional method.

Abstract

A dry deposition model suitable for use in the moment method has been developed. Contributions from five main processes driving the deposition - Brownian diffusion, interception, impaction, turbulent impaction, and sedimentation - are included in the model. The deposition model was employed in the moment method solver implemented in the OpenFOAM framework. Applicability of the developed expression and the moment method solver was tested on two example problems of particle dispersion in the presence of a vegetation on small scales: a flow through a tree patch in 2D and a flow through a hedgerow in 3D. Comparison with the sectional method showed that the moment method using the developed deposition model is able to reproduce the shape of the particle size distribution well. The relative difference in terms of the third moment of the distribution was below 10\% in both tested cases, and decreased away from the vegetation. Main source of this difference is a known overprediction of the impaction efficiency. When tested on the 3D test case, the moment method achieved approximately eightfold acceleration compared to the sectional method using 41 bins.