Thanks for your reply Rob,

What you said is exactly correct. Over the 1e-4s of injection time, 1000 parcels are injected from each facet. I have about 700 inlet facets, and my total number of injection groups is 11. All in all, there are about 8 million parcels to be tracked. I don't think that this is a significant number. Do you?

You didn't answer my question specifically though. Is there any way that I can change my core allocation to DPM in the software settings? The solution time doesn't change no matter how many cores I allocate to the job. Again, it takes much less time to track DPM in steady mode. I understand that in the steady case, it will be a one-time injection from each facet for each of the 11 injection groups. Therefore, there are 1000 times more particles in the unsteady mode.

However, the first one takes a few seconds while the latter takes more than a week to be solved. The difference in time is not reasonable. So, I am suspicious that something is not right in the core-allocation settings in the unsteady case.