A negative gas volume fraction

MFiX
#1

Hello,
I use TFM.When I run my case, the time step gets smaller and smaller, and some error files are printed indicating that the gas volume fraction is negative. solid1 volume fraction is greater than 1.

1669635274(1)
1669635274(1)722×422 9.04 KB

How can I solve this prolem and avoid this problem?
Thank you!

#2

It is hard to tell without more details. Did you disable close packing? Please attach your simulation files if you want someone to take a look.