Penetration of particles through vertical cracks

Abstract

In a previous study, a new deposition model was developed to account for deposition of aerosol particles on the inner walls of small containers. In this article, the model applicability is extended by including deposition on horizontal surfaces, both upward-facing and downward-facing. After that, the model is applied to study a vital new issue, which is the penetration of aerosols to the indoors through vertical wall cracks. Previous studies, both theoretically and experimentally, never addressed penetration through vertical cracks. This study therefore aims to show the difference between penetration through vertical cracks and horizontal ones by applying the fourth-power model, which is very successful in describing deposition in small volumes. The penetration model formulated in this study takes into account, not only the thickness and depth of the crack, as usually happens in most penetration models, but all the three dimensions of the crack; thickness, depth and width. The obtained results are in a good agreement with the experimental data. This demonstrates the success of the extended fourth-power model in describing deposition inside cracks. Moreover, the results show a clear difference between vertical and horizontal cracks for the penetration of aerosols with diameter larger than ∼1μm. An application of the developed deposition and penetration models is presented, where a method for calculating the radioactive aerosols indoor concentrations is explained.