Numerical Simulation for Prediction of Saltation Velocity for Gas-Solid Two-Phase Flow in a Horizontal Pipe.

The saltation velocity (or the critical velocity) for coarse particles is predicted numerically, where the particle motion is traced by the Lagrangian approach by considering the fluid drag, gravity force, Magnus force, and Saffman force acting on the particles, whereas the gas flow is calculated by the marching method. The interaction between gas and particle is considered on the level of mean gas flow. It is assumed that the total pressure drop in a region of terminal velocity of particles consists of two parts, one due to the gas alone and the other due to the fluid drag. The fluid drag consists of the particle source term in the equation of motion for the gas, where the change in fluid drag due to particle-particle collision as well as particle-wall collision is considered. The result is quantitatively compared with several well-known empirical formulae for the saltation behavior.