The Effect of Subgrid-scale Turbulence on LES of Inertial Particle Transport in a Boundary Layer Flow*

Investigation of particle dispersion in boundary layer flows is of great importance in several environmental applications, such as atmospheric pollutant dispersion and ember tracking during wildfires. In these and many practical cases, the accurate tracking of particle trajectories across large spatial and temporal scales requires the use of Large Eddy Simulations (LES). However, one of the main limitations of LES is its inherent filtering of smaller-than-filter size (subgrid-scale (SGS)) flow features, which can compromise the accuracy of particle transport models. These filtering-induced inaccuracies accumulate over time, leading to increasingly higher errors as the spatial and temporal scales of the simulation increase. In this work, we employ a structural SGS model to account for and investigate the effects of sub-grid turbulence on the transport of particles in a boundary layer flow. We focus our analysis on settling particles of different sizes, while identifying the mechanisms governing their distribution within the flow. When comparing against Direct Numerical Simulations, the SGS model improves both flow and particle statistics, leading to a better prediction of landing distributions across a wide range of particle sizes.