Fixed bed volume fraction

I try to model a cylindrical fluidized bed for finding the minimum fluidization velocity. The fixed bed volume fraction is 0.62 and its height is 6.88cm. I use a “bed” region and I.C to define this condition But at the start of simulation the bed collapse and height decrease.
How I can define a fixed bed with a constant solid volume fraction and height?

Would it be possible to enforce your solid volume fraction as a boundary condition (BC) rather than an initial condition?

I don’t think so.
Because the bed is going to be fluidized with increasing the gas velocity. And the boundary conditions are constant during the simulation.

I’m afraid I misunderstood the question - you said you wanted constant volume fraction? Doesn’t that mean that it remains constant during the simulation?

As shown in the figure below, I define a fixed bed with the specifications that see on the left side. But when the simulation starts the bed is collapse and specifications change!

The video below shows the collapse of the bed:

But when I use TFM, This does not happen for bed.

Just started out using MFiX, but if I’m not mistaken, you cannot disable the momentum equations in the DEM mode.

In the following image, you can see that you are unable to modify the momentum solvers. To me this implies that the DEM is automatically modeled as a fluidized bed. I could be wrong, however.


Do you want to disable the CFD part and only use DEM (no fluid and only pure granular flow)?
If I understood correctly, you should check the “disable fluid solver” in the model setup.