Density of part of particles becomes zero when using cyclic boundary

Hi, everyone,

When i was running the tutorial case fluid_bed_dem_2d, I added some line of code in the module calc_force_dem, as shown below. The source code is also attached below. The aim of these code is to check whether the particle density of two neighbour particles is the same or not, while the diameters of those particles of different density are also recorded. In addition, i added two cyclic boundaries in the BC, as in the attached file.

calc_force_dem.f (12.8 KB)
fluid_bed_dem_2d.mfx (8.1 KB)

After running, as shown in the file “out.dat”, density of part of particles became zero which was not correct, but the diameter of particle was always correct.

On the other hand, when i canceled the cyclic boundaries, everything became okay. So i guess the density of particle may not be updated or there may be an error.

By adding the attached source files to the tutorial case folder, you can try it. And can you please tell me how to fix this “error”?

Notice: if you want to try it, please change the path of output file in calc_force_dem.f