A model for the prediction of a particle laden turbulent free shear-layer including large-scale structure effects is presented. The Eulerian formulation has been used for the carrier phase flowfield while a Lagrangian formulation has been employed for the dispersed particles. The carrier-phase mean flow has been determined from the classical turbulent boundary layer equations including interaction terms with the large-scale structure. A traditional two-equation turbulence model (k-ε), modified to include large-scale structure effects, has been used for the determination of the small-scale turbulent stresses. Ideas from non-linear stability analysis have been utilized to model the large-scale structure as a spatially growing wave. The Lagrangian equation of particle motion has been used in its simplest form, neglecting Basset history and virtual mass terms as well as lift forces. The effect of the carrier phase small-scale turbulent fluctuations have been taken into account by using a classical stochastic model with a gaussian PDF. The computational effort required by this model is orders of magnitude less than that required by LES or DNS for the same problem. The flow model has been used to obtain, for the first time, results of particle trajectories in a spatially developing mixing layer forced by a single frequency. Our results indicate that large-scale related parameters such as the forcing frequency, large-scale structure energy, and particle injection phase relative to the large-scale structure have a profound influence on the motion of the particles and their distribution within the mixing layer.
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