How to adjust des_epg_clip to get a specific bulk void fraction?

[KAMAL_KISHOR_PANDEY]

Hello @jeff.dietiker @cgw .
I am working on validating the pressure drop in a lab setup with a homogeneously mixed bed of binary particles, using simulations conducted in a scaled-down geometry. The packed bed void fraction in the experiments is 0.36. How to seed the particles at a specific void fraction.

I manually performed all the calculations to create a homogeneously mixed bed of binary particles, but the resulting bed was slightly densely packed and had a void fraction of 0.34. How can I generate a bed with a specific void fraction?

I conducted several runs by adjusting the des_epg_clip value. Modifying this parameter alters the local void fraction in each cell, which in turn affects the pressure within the cells. How can I adjust this value to achieve the same bulk void fraction as observed in the experiments? any help would be apprieciated. Thanks in advance. I would appreciate it if you could respond at your earliest convenience.

[cgw]

Hi @KAMAL_KISHOR_PANDEY

As always it is helpful if you attach your case file.

I believe that des_epg_clip affects the computed void fraction, not the actual void fraction. If I understand you, you want to create a packing with a specified void fraction of 0.36. How are you creating the initial packed bed? Are you using automatic particle generation in MFiX or did you create a particle_input.dat file? (Note that in MFiX 24.3 we have moved to a more convenient particle_input.csv format). Automatic particle seeing in MFiX is lattice-based and doesn’t deal well with a mix of particle sizes, because the lattice is set to the size of the larger particle.

As the particles settle under the influence of gravity, they will achieve a packing density determined by the mix of particle diameter… I don’t think you can force a specific void fraction. But maybe I am misunderstanding what you are trying to do!

– Charles