Large-eddy simulation of the flow behaviors of gas and particles in a riser

Transport equations of gas-solid flows are filtered by means of the volume fraction weighted average method. The filtered equations for gas phase and solid phase are derived, and Euler-Euler two-fluid large eddy simulation model of dense gas solid flows is presented. The model is used to simulate the hydrodynamics of gas-solid two-phase flows in a riser. The model predicts the core-annular structure of particles flow. The time averaged particles concentration and velocity are obtained and agreed with Knowlton et al. experimental results. With the increase of coefficient Cs, the particles fluctuation velocities are decreased in the centre region, and opposite to the near-wall region. The time-averaged particles turbulent kinetic energy is decreased with the increase of coefficient Cs.