ABSTRACT
Gravel-bed rivers display a large variety of particle sizes and shapes. However, effects of collisions among particles in different sizes on particle motions and bed structures are hardly clarified. This paper presents results of a numerical simulation with a numerical movable-bed channel capable of simulating three-dimensional motions of flows and particles in different sizes and shapes. The numerical simulation revealed differences in action directions of contact forces of particles in different sizes and effects of particle-volume concentrations on particle collisions. The simulation also demonstrated that collisions among particles in different sizes strongly affected particle motions and vertical structures of the movable bed.
