Loose distribution of particles under normal Particle Size Distribution

Hi everyone

I am studying simulations for fluidized beds and I have a question about initial particle size distribution. In the photo below, particles show a loose distribution even if I have change the particle spacing to zero in the initial condition pane for solids. However, particles could array closely in Fig. 4.8(d) of MFiX User Manual (see 4.8. Initial Conditions — MFiX 21.3 documentation). I am not sure how to solve this problem.



Kindly regards

Particles are placed on a lattice which spacing depends on the largest particle size (this is the minimum spacing). The spacing factor can increase the spacing, setting the spacing factor to zero means there is no extra space in the lattice. The difference with Figure 4.8 is that the ratio between large and small particles is larger in your case.

If you cannot fit the initial inventory in the domain, I can think of two options (I am assuming you have a continuous particle size distribution):

  1. Write your own particle generation code and save the data in a particle_input.dat file to use as initial condition: 8.4. Frequently Asked Questions — MFiX 21.3 documentation

  2. Set up a granular flow simulation with a taller domain so you can fit the desired inventory. Let is settle for a while and save the particle positions at the end of the run. Go to the Output pane and select Save particle positions at end of run and reset particle velocities to zero in particle_output.dat. This will save the particle data in a file called ‘particle_output.dat’. You can inspect and edit the file if necessary and if satisfactory, rename it into particle_input.dat and use it as the initial condition for your actual simulation.

Thanks for your suggestions. They are good ideas.