Numerical study of ultrafine particles dispersion in the wake of a cylinder

Özet

The dynamics of ultrafine particles are strongly dependent to the airflow topology. In this study, the dispersionof carbon nanoparticles in the wake of a cylinder placed in an airflow at Reynolds number of 9300 is nu-merically investigated. An Eulerian/Lagrangian approach is used to compute the two-phaseflow; the carrierphase is predicted through a RANS (Reynolds Averaged Navier-Stokes) model while a particle Lagrangiantracking method provides the trajectory of each nanoparticle. The present numerical investigation allowsstudying the influence of Brownian and turbulence effects on the nanoparticles dispersion. The main resultsreveal that: (1) The Brownian diffusion tends to concentrate the carbon nanoparticles in the form of afilament atthe periphery of the vortices that are generated in the cylinder wake. (2) The turbulence increases the lateraldispersion of the nanoparticles. It disperses them from the edge to the core of the vortices. (3) The highestconcentration levels decrease from the near wake of the cylinder to the far wake region while the lateral dis-persion increases.