The Numerical Simulation Of Granular Material Transportation Of Dem Based On CPU-GPU Heterogenous Computers

Particulate matter is a complex system that composed of a large number of discrete particles, because of its ”loose” and ”dynamic” special mechanical characteristics, the microscopic mechanism and macroscopic behavior of particle system are vary di?cult to know well, so it will bring many deviations between theory and reality under the macro theory for continuum mechanics. The discrete element method is an important model to describe the law of motion and the kinetic characteristics of particles, it has become an important method to solve this problem.With the geometrical model of high resolution putting out, and the requirement for the computer capacity and speed growing rapidly in numerical simulation, the computation cost and memory capacitance has become a major bottleneck for the application of large-scale DEM, parallel computing is an e?ective way to solve the problem. In this work, for a class of discrete element model including liquid bridge force, the parallel program was implemented based on CPU-GPU heterogeneous computers, and the emergency brake process in granular material transportation based on the parallel program was carried out.The numerical simulation of the emergency brake process in granular material transportation was carried out based on the program including the liquid bridge force. Firstly, the mathematical model without liquid bridge force of granular material transport was completed, and then the serial solver of DEM considering the liquid bridge force is attained, the model with liquid bridge force was discussed,and the corresponding serial solver also developed, the comparison of numerical experiments between wet and dry granular system is also successfully achieved, the e?ect of liquid bridge force to force distribution and the accumulation of particles are also discussed, it is found that the particles concentrated in front of the truck in the brake process with a slope forming on the upper surface of the agglomerating particles. When the liquid bridge force was considered, the force acting on both the bottom and front wall of the truck was higher, the particles moved more slowly,the slope was gentler.Based on the CPU-GPU heterogeneous computers, the parallel solver for the above mentioned DEM model was implemented, the main steps are as follows:(1)dynamic creation of the essential arrays according to the solving system, the serial solver is developed,(2)based on it, the corresponding parallel solver was designed with the technology of reasonable data structure for the sake of avoiding memory accessing collision used. The numerical experiment of the emergency brake process in granular material transportation based on the parallel solver was carried out, it is shown that the new parallel solver gives a positive mathematical behavior of serial solver and also has a good parallel speedup ratio,for example, on the NVIDIA Tesla K40 c card along with Intel Xeon 3.00 GHz CPU, the average speedup 13.01 was obtain.