Simulation of dense gas-particle flow using a USM-θ model, combined with a frictional stress model

A unified second-order-moment (USM) two-phase turbulence model together with a kinetic theory of inter-particle collision (USM-θ), and combined with a frictional stress model, was used to simulate dense gas-particle flows in a downer reactor. The interaction between gas and particle turbulence is simulated by a transport equation of two-phase velocity correlation. The simulation results are in good agreement with experimental data reported by Wang et al. The typical dense ring of particles in the near-wall region was observed. It is found that the frictional stress affects the particle fluctuation energy dissipation, leading to the decrease of the particle pseudo-temperature. Because particles are not dense enough in the center region, the effect of inter-particle collision on particle fluctuation velocity, gas-particle velocity correlation, particle collision frequency, particle shear viscosity and particle effective thermal conductivity are not obvious.