The Effects of turbulence on metal nanoparticle nucleation in turbulent jets.

Abstract

The effects of turbulence on nanoparticle nucleation are studied using a combination of fully resolved and large-scale quantities from direct numerical simulations. A size de- pendent model for homogeneous nucleation captures the formation of zinc nanoparticles. Growth of these particles is considered by Brownian coagulation. Three simulations are performed using a single Reynolds number and vapor mass-fraction. In one simulation nucleation is computed with fully-resolved data while the remaining two compute nu- cleation with large-scale filtered data, each at different filter-widths. In all simulations

fluid and scalar quantities are fully resolved. A nodal method captures the resultant particle field, approximating the general dynamic equation. Comparisons between the three simulations are made in order to asses the role small-scale turbulent features play on nucleation. Results show that nucleation occurs primarily along the shear layers. Unresolved subgrid-scale nucleation acts to both increase and decrease nucleation. The predominant effect is to decrease nucleation. This leads to an over-prediction of nucle- ated particles when neglecting the small-scales. The over-prediction is largest in laminar and transitional flow regimes and increases with filter width. No significant discrepan- cies are seen in the size of nucleated particles when using large-scale quantities.