Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe

Lagrangian-type numerical simulation was carried out on plug flow of cohesionless, spherical particles conveyed in a horizontal pipe. The motion of individual particles contacting each other was calculated using the equations of motion and a modified Cundall model. Forces between particles were expressed by using the Hertzian contact theory. The Ergun Equation was applied to give the fluid force acting on particles in a moving or stationary bed. The flow patterns obtained in the present work appear to be realistic. The wave-like motion of the flow boundary reported previously by several other researchers was observed clearly in the simulation. Also, good agreement was obtained for the relation between the height of the stationary deposited layer and the plug flow velocity. Due to the limitations of computation time, only the case of large particles (ie. d > 10 mm) could be considered here.