Mass flow rate variation with time step in MFIX-DEM

MFiX
1

Hello,

I am comparing DEM MFR with different time step (automatic time step with factor 10 giving 2.8E-7s and constant time step 3E-6s) in Mfix-Dem.

I don’t know why there is so much variation.

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Please suggest me to resolve the issue.

2

This is not an issue, you should expect CFD results to be sensitive to time step. We don’t recommend arbitrarily increasing the DEM time step.

3

Thanks for your response.

The MFR at time step = 3E-6s is approaching closer to the experimental MFR at steady state.

But I can’t able to minimize the variation of MFR between experiment and simulation with time step = 2.8E-7s