How to generate particles of different sizes in MFIX-DEM?

MFiX How to
#1

I want to generate small(d=0.2mm) and large(d=3mm) particles in a rectangle region.
At first, I tried to generate small or large particles with the command of gener_part_config, and it worked.
But when I attempted to combine them, the calculations seemed to be wrong.
So how can can I generate particles of different sizes in MFIX-DEM?
Is it only possible to generate it with the particle_input.dat file?
Thank you very much!

materials
materials695×143 3.14 KB

DEM
DEM680×780 14.9 KB

initial%20conditions

#2

When initializing particles of different sized in the same IC region, they will be seeded with on a lattice with a spacing based on the largest particle. This can lead to large discrepancies between specified and actual volume fractions. Please try the following:

  1. Increase the IC region extent in the y-direction. This will give more room to seed particles and it may help get closer to what you want.
  2. Define 2 IC regions on top of each other, each with only one solids phase. This should help for the smallest particle size
#3

I tried to define 2 IC regions for each solids phase, but the solver didn’t work with an error about the 2 IC regions.
IC1 IC2
error

Besides, the segregation of binary mixture has been validated in a bubbling bed with MFIX-DEM ( Li et al. 2012), so if it is possible to provide a tutorial like that?
Really thanks!

#4

So the error message is telling you that you have overlapping ICs with non-zero ic_ep_g, which is not allowed. It looks like you are trying to define an IC with two different solids? Why not just use one IC that defines both solids?

#5

I tried this way， but the result is wrong. Jeff said that is because “they will be seeded with on a lattice with a spacing based on the largest particle. This can lead to large discrepancies between specified and actual volume fractions.”

#6

I wasn’t clear. I should have said create two IC regions, stacked vertically, with no overlap. For example, IC#3 goes from y=0 to y=0.02 and IC#4 from y=0.02 to 0.04. IC#3 contains phase 1 particles and IC#4 contains phase 2 particles.

#7

Hi, Jeff

Is it possible to create a region with binary particle mixture, i.e. particles are mixed in the defined region? As mentioned above,

in the mentioned paper, particle mixing was made by definition in the initial condition rather than fluidization at high gas flow. However, when i define two solid volume fraction in the region, it generates two separated solid phases. So, can you please tell me how to make it?