Numerical simulation of concrete pumping process and investigation of wear mechanism of the piping wall

A numerical simulation has been conducted to study the solid-fluid multi-phase flow problem in concrete pumping process. The kinematics and trajectory of the discrete particles as well as the particle-particle interaction were predicted by DEM while the motion of the continuous fluid phase was evaluated by a Navier-Stokes solver, and a pressure gradient force model was adopted to calculate the solid-fluid interaction force. A case of pneumatic conveying was utilized to demonstrate the capability of the coupling model. The concrete pumping process was then simulated, where several flow features were observed such as roping, particle segregation and particle concentration. The frequency of the particles impacting on the bended pipe was monitored, a new time average collision intensity model based on impact force has been proposed to investigate the wear mechanism of the elbow. The location of maximum erosive wear damage in the elbow was predicted. Statistical results were in good agreement with that observed in actual pumping process. It is found that the present multi-phase coupling model can predict the wear behavior of the bended pipe accurately, and consequently provide an effective guidance for the design of concrete pumping pipe.