Why can't the simulation continue after the inlet velocity is set to 0?

Hello, researchers! In MFIX-DEM, the fluidized bed I simulated has no problem in the process of fluid entering from the bottom. However, changing the fluid velocity to 0, that is, the process of falling back particles, always reports DT<DT min. I changed the inlet velocity to 0 after the fluid entry ended and restart-resume. DT<DT min error is always reported when the simulation is carried out until the particle velocity is very small. What is the reason for this? My goal is to reduce the speed of the particles to zero, how do I change that? Relevant documents have been uploaded, looking forward to answering! Thank you!
1.zip (7.6 MB)

Hi @Tongkun_Dai - sorry for the delayed response. I’ve been looking at your case and don’t see a divergence (mfix-23.3.2). But it looks like you got the divergence at t=32 and I only ran it out to t=2 (24 hours on a single CPU). It looks like you are using SMP with 99 threads. I currently do not have access to a host where I can run 99 threads. This might be an SMP bug, have you tried running in DMP?