Hello researcher, I would like to consult you about DEM particle generation. I want to generate particles of two different sizes that are mixed with each other (randomly generated). How can I achieve this? Currently, my results show that the two types of particles are clearly layered with one on top of the other.
small-bf_2026-03-02T150414.691134.zip (147.2 MB)
I have made some attempts. At present, mixed particles can be generated, but the spacing between particles is very large (is it because the diameter of my larger particles is very large?). I modified the particle spacing in the dem seeding option, but it does not seem to improve. I know that the particle spacing is set by the diameter of the largest particle, but is there any way to make the particles more compact?
small-bf_2026-03-04T215644.691036.zip (169.9 MB)This is my relevant file.
The best approach for what you are doing is to write your own script to generate the particle input file. The automatic particle generation in MFIX is limited, as you have seen, and uses a lattice based on the largest particle size.
In the mfix source directory you will find tools/particle_gen.c which is a C utility that places particles randomly and can sometimes achieve higher density. You would have to modify this for the different particle sizes.
There’s also an older Fortran program in DES_Particle_Generator
Or you could start from scratch using Python (maybe the easiest if you are not familiar with C or Fortran).
Please let us know if you require further help with this.
– Charles
I have realized the random initialization of particle position information through the function of the following figure.
By the way, I want to ask why DES simulation doesn 't support Semi-permeable.
small-bf_2026-03-17T205320.914973.zip (145.7 MB)This is my file.
Semi-impermeable internal surfaces are meant to be used for TFM, where we specify internal resistance and solids velocity. This has not been ported to DEM and is thus not available.
