Experimental and numerical characterization of the concentration distribution of particulate pollutants inside a full-scale car cabin

Abstract

We report an investigation of particle dynamics through measurements of particle concentrations inside a full-scale car cabin and comparing the results to numerical predictions obtained using the ”Diffusion-Inertia Model” (DIM) for particle transport, coupled with the RANS approach for single-phase flow. Measurements were conducted by placing the vehicle in a closed chamber where a homogenized atmosphere was generated and controlled, enabling the study of fine and ultrafine particle infiltration by measuring the particle mass concentration distribution inside the vehicle’s cabin. A comparison between numerical and experimental results for particle concentration profiles of PM₁ and PM₁₀ showed that the numerical model reasonably reproduces the experimental results, particularly for low-inertia particles. Both numerical and experimental analyses revealed a tendency toward particle concentration homogeneity within the compartment. Additionally, the influence of ventilation velocity on the dynamics of $1\mu m$ and $10\mu m$ particles was investigated numerically. The results indicate that increasing airflow velocity accelerates the homogenization of particle concentrations, while inertia effects become more pronounced, leading to lower concentration levels due to particle deposition on cabin surfaces. The effect of thermal buoyancy on particle transport was also examined. While the overall dispersion patterns remained largely unchanged, localized variations were observed, particularly in the passenger breathing zone, where thermal effects reduced particle concentration.