A Systematic Review of Fluid Mechanical Models of Respiratory Aerosol Transport in Airways: Methods, Architectures, and Future Research Directions

Abstract

Respiratory aerosol transport within human airways has emerged as a critical area of research due to its significant implications for pulmonary drug delivery, airborne disease transmission, and environmental exposure assessment. Fluid mechanical modelling plays a central role in understanding the complex interactions between airflow, particle dynamics, airway geometry, and physiological processes such as mucociliary clearance. This review provides a comprehensive analysis of modelling approaches used to simulate aerosol transport in the respiratory tract, including one-dimensional whole-lung models, three-dimensional computational fluid dynamics (CFD), large eddy simulations (LES), Reynolds-averaged Navier–Stokes (RANS) methods, and hybrid CFD–discrete element method (DEM) techniques. These frameworks enable detailed predictions of aerosol deposition, transport pathways, and residence times across different airway regions. Recent studies emphasize the influence of turbulence, particle size distribution, airway geometry, and breathing patterns on deposition efficiency and spatial distribution. Advanced CFD models show strong agreement with experimental and imaging techniques, supporting their use in patient-specific analysis. Additionally, emerging approaches incorporate multiphase flow physics, mucus rheology, and particle–wall interactions to enhance physiological realism. Despite these advancements, challenges remain in model validation, computational cost, and multi-scale integration, indicating the need for more efficient and comprehensive modelling strategies.