silo problem

Submitted by adabubu on Mon, 11/18/2013 - 15:43


my simulation is about silo. Particles are poured into a silo (cuboid 0.58m * 0.875m*2m). Due to highly overlapped atoms are involved, so I used "fix nve/limit" to define the nve intergration. After particles are poured into the silo, i used "wiggled" for getting better packing, however the numerical results of pressures on walls are larger than them from Janssen equation (about 30% larger , then I tried to "unfix nve/limit" and use " fix nve/sphere" after pouring particles, while the pressures on the wall are still larger than them from Janssen equation.
And at same time I also did two other simualtions with a cubic silo (0.6m*1m*2.0m) and a cylidner with 1m diameter. I compared the nuemrical results of pressures on walls with Jassen pressures. And they showed a good match. In those simualtions, I used "fix nve/limit" and " fix mve/mesh wiggle". I felt it is very strange that these three simulations showed such difference when they are compared with Janssen, even though the only difference among them is only the difference of geometry of silo. Anyone could give some some tipps about this? Thanks a lot!