A numerical study on dispersion of particles from the surface of a circular cylinder placed in a gas flow using discrete vortex method

The dispersion of particles emitted from the surface of a circular cylinder placed in a gas flow at the Reynolds number of 200 000 is numerically investigated using the discrete vortex method coupled with a Lagrangian approach for solid particle tracking. The wake vortex patterns, the temporal-spatial distributions and trajectories as well as the dispersion functions for particles with various Stokes numbers (St) ranging from 0.001 to 1.0 are obtained. The numerical results reveal that: (1) Solid particles on the cylinder surface are picked up and then transported away from the cylinder by the wake vortex flow. (2) Solid particles emitted from the cylinder surface always follow the vortices in the cylinder wake, and the response of particles to wake vortices is directly related to their Stokes numbers (particles with St=0.001, 0.0038, 0.01 can distribute both in the vortex core and around the vortex periphery, whereas those with St=0.1, 1.0 can not enter the vortex core and congregate mainly around the vortex periphery). (3) The particles move in rolling state in the wake region, and the dispersion intensity of particles in the lateral direction decreases remarkably as the Stokes number of particles is increased from 0.001 to 1.0.