Why the particles slipped out from the left and right walls

MFiX
1

hello everyone:
I used the mfix-dem 22.2.2 to simulate a fluidized bed.
the van der waals cohesion model is used in the case. however, the particles slipped out of the bed from the left and right walls.
I don’t know what caused this?
the case is uploaded as below:
test-123 (another copy).zip (9.1 MB)

2

Please upgrade to MFiX 25.1.2