Two-dimensional simulation of solid-liquid flows in a vertical pipe was carried out. Trajectories of the particles were obtained using the Lagrangian method with a deterministic interparticle collision model and irregular bouncing of particles off the pipe wall. Local mean velocities of the liquid phase were simulated from the equations of continuity and motion by the SIMPLE scheme taking into account the fraction of the fluid and the drag force. Six types of simulations were compared using glass beads with a diameter of 2 mm ina vertical pipe. Some of the simulations showed quite different particle configuration and fluid velocity. The results indicated that reliability in modeling a flow containing solid and interparticle interaction is a key issue for accurate simulation of solid-liquid flows.