Nanoparticle coagulation in a planar jet

Direct numerical simulation of nanoparticle coagulation in a planar jet is performed. The particle field is represented using a sectional method to approximate the aerosol general dynamic equation. The methodology is advantageous in that there are no a priori assumptions regarding the particle size distribution and coupled with an unsteady Navier-Stokes solver, it provides the spatio-temporal evolution of the particle field in an accurate manner. The jet consists of an incompressible fluid containing particles 1 nm in diameter issuing into a particle-free coflowing stream. Ten sections are solved allowing the particle field to develop to 8 nm in diameter. Results show that the geometric standard deviation reaches the self-preserving value within one jet diameter downstream of the nozzle and remains at that value up to 7.5 jet diameters. In this proximal region, the particle size is relatively uniform throughout the jet. Further downstream, the effects of large-scale vortical structures is to increase the residence time of particles within the domain and perturb the geometric standard deviation beyond the self-preserving value.