عنوان مقاله [English]
Turbulent backward step flow including air and copper nano particles has been simulated using Computational Fluid Dynamics (CFD) method by Eulerian-Lagrangian method. The simulation was done in two and three-dimensional methods with CFX and FLUENT software. The obtained results were compared with each other and with the experimental results. The two-way coupling discrete phase model (DPM) was used for simulation. The Saffman lift force, pressure gradient and turbulence effects on nano particles are considered. Numerical results obtained with Eulerian-Lagrangian models and single-phase model in steady and transient have been compared with experimantal data. The effect of the turbulence model on the trajectory of particles and in terms of different diameters of 10, 20, 30, 50, 70, 100 and 200 micrometers have been investigated. The effects of particle diameter on the trajectory and behavior of particles and the effect of Stokes number on the presence of particles in the vortex created behind the step have been investigated.The results have been presented as varies contours and graphs for two and three dimensional, steady and transient states. Particles trajectory are shown as contour for different Stokes number and particle diameter. The continues phase velocity variation across the channel for different distance of step present as graphs. Standard, RNG and Realizable k-e and standard and SST k-w models are considered for the modeling of turbulent flow. The results reveal that SST k-w has better accuracy than the experimental. The results show that SST k-w is more accurate compared to the experimental data.Furthermore, simulation has been done with CFX software. Variation of velocity profile are compared with experimental and Fluent data for different distances of step.The results show that the Stokes number and the turbulence model have a significant effect on the trajectory of particles. Three-dimensional modeling of the flow increases the accuracy of the results.