Numerical simulation of the interactions between a vortex pair and solid particles near a wall

This study simulates the interactions between a vortex pair and solid particles near a horizontal wall in the air. Two counter-rotating vortex tubes are moved toward the particles, initially arranged in regular layers above the wall. The Reynolds number of the vortex tube is 1000, and the Stokes number is 1. The particles near the edges of the layer are whirled up by the vortex tubes approaching the wall, while the inner particles are driven toward the wall. The whirled up particles distribute circularly around the vortex sheets rolled up by the vortex tubes. The initial particle layer and the whirling particles induce three-dimensional vortex structures and also decrease the circulation of the vortex tubes. The velocity difference between the particles and the air creates a drag force that effectively increases the wall height and suppresses the approach of the vortex tubes toward the wall.