Numerical Study of Particulate Pollutants Removal by Ventilation, Portable Air Cleaner, and Gravitational Settling Across Particle Sizes

ABSTRACT This study numerically investigates the removal of indoor particulate pollutants of various diameters by ventilation, a portable air cleaner, and gravitational settling using a drift‐flux model within a computational fluid dynamics framework. The drift‐flux model is first validated against a benchmark particle dispersion experiment, showing good agreement with measured velocity and concentration. Simulations are then conducted for an L‐shaped room equipped with ceiling ventilation and a portable air cleaner placed at four locations. Particles ranging from 1 to 50 μm (particle density: 1.6 × 10 3 kg/m 3 ) are considered uniformly generated. The relative contributions of ventilation (air change rates (ACH) of 0.5 and 2), air cleaner intake (ACH of 3.15), and gravitational settling are quantified. Results show that the air cleaner dominates removal for particles smaller than 10 μm, whereas gravitational settling governs particles larger than 10 μm. Considering no surface deposition or resuspension, the cleaner placement minorly influences overall removal efficiency. A one‐node model based on an equivalent ACH framework is proposed to compare its predictions with CFD results. Although the one‐node model cannot represent spatial variations, it captured overall trends in particle removal. This study provides insights for evaluating particle removal strategies and optimizing air cleaner use in indoor environments.