A transverse Stokes number for the lateral migration of particles near the leading edge of a flat plate

Particle migration in laminar boundary layers is extensively studied, but in the near-leading-edge region, this process is not fully understood, yet. In this paper, the lateral migration of heavy particles entering the laminar boundary layer near the leading edge of a flat plate is investigated. First, numerical and analytical studies show that the high-vertical-velocity zone outside the laminar boundary layer near the leading edge plays a key role in the particle's lateral migration. Then, based on the analytical result, a transverse Stokes number which accounts for the effect of the high-vertical-velocity zone and the particle's lateral inertia is proposed. Finally, results of twenty-seven simulation cases are collected and analyzed, and this number is proved to be a more suitable criterion than the Stokes number in predicting the particle's lateral migration regime near the leading edge of a flat plate.