MP-PIC simulation of dilute-phase pneumatic conveying in a horizontal pipe

Dilute gas-solid two-phase flows inside a pneumatic conveying pipe are simulated with the multiphase particle-in-cell (MP-PIC) method. To achieve high simulation accuracy, different particle-wall collision models, drag force models and turbulence modulation models have been tested. Simulation results including pressure drop, gas and solid mean velocities, fluctuating velocities are compared to experimental measurements. It is found that the particle-wall collision restitution coefficient, especially in the tangential direction, significantly influences the total pressure drop. The mean particle velocity and slip velocity are sensitive to the drag force and a much higher drag force can improve the simulation accuracy, whereas the mean gas velocity is not sensitive to the drag force. The fluctuating gas velocity is hard to be predicted with the currently available turbulence modulation modeling choices, implying more efforts are needed in understanding the turbulence in future.