For a Fluidized bed I’m trying to achieve similar results as in a physical test that has been done. As the particles are crystal-like and often somewhat irregular, it is observed that the theoretical terminal velocity is actually quite a bit higher than the actual. Is there a way to tune the drag model, or choose a more suitable one, so that the drag is modeled better? These are for beds with size class ~100microns.
(side question: to capture the air movement over the bed, I looked for improved discretization schemes, compared to the default upwind. Would the dwf upwind be better, or are there other which would work better for advection terms?)
This is not a complete answer, but I wanted to note that non-spherical particles are a feature that is coming to MFiX in version 21.3 or 21.4, if you can wait for that.
Thanks, this is good news! Looking forward to this feature.
But I have to come to an end here within quite short time, so I’m considering to adjust the particle diameter (to get the right drag), and then the density, so that the forces are equal. This approach will probably not be quite correct for what’s happening inside the fluidized bed, mostly above, but hopefully the diameter change will only be moderate, and so it will be not that bad afterall.
I notice the default drag model does have two tunable parameters, so perhaps could this also be an option to look into, but I fear that requires some extended test knowledge from the bed itself to get everything right.
Try the Defelice-Ganser drag, which is for non-spherical particles fluidization. There are two parameters, the first one is the sphericity and the second one is the bed diameter.
