PDF-PBE for particle dispersion in a turbulent round jet

The probability density function form of the population balance equation (PDF-PBE) is employed in the large eddy simulation context to simulate the dispersion of droplets in a round turbulent jet. Test cases studied here include the injection of 60 and 90 μm droplets into a turbulent air jet with Re of 20,000 and 30,000. A newly developed Stokes binning method is used to account for the differential inertia of droplets of different sizes and to partition the PDF-PBE into classes based on the droplet Stokes numbers. The method leads to accurate modelling of the different trajectories that are followed by particles with different sizes in a computational tractable manner. A Langevin model is employed to reconstruct the subgrid scales in the carrier flows. The PDF-PBE model reproduces the radial dispersion and the mean droplet velocity fields very well. It is found that the direct effects of the subgrid scales on the dispersion of 60 and 90 μm droplets are insignificant in the present flow cases.