How to fix "particle velocity greater than the maximum value" in CFD-DEM simulation?

MFiX
#1

Hi Dear MFIX Team,
I met this problem when I run CFD-DEM simulation. Please see the following picture. I just want to know what I could do to fix it? For example, adjust some important keywords in mfix.dat. Thank you so much. The time step for particles is about 10^(-6) s, and the normal stiffness is 8000 N/m.

CFD-DEM-VelocityHigherThanMaximum
CFD-DEM-VelocityHigherThanMaximum1526×552 62.6 KB

Best regards,
Leina

#2

The message from the solver is that the fluid velocity is to high. The fluid velocity in one cell has a magnitude greater than 107 m·sec-1).

  • If you are running with cut-cells, you need to make sure your mesh is good.
  • The output shows that you are running with a fixed time step (DT_FAC >=1.0). You can either enable the automatic time step adjustment by not specifying DT_FAC, or, if you want to run with a fixed fluid time step, reduce the value of maximum time step size (DT_MAX) to something that works for all flow conditions.
#3

@jmusser I faced the same error in TFM and I am almost sure that it is due to the mesh quality. I have a FB with a conical frustum shape and I have tried a lot to enhance the quality of the grid but I think it did not work. Would you please tell me how to check the mesh quality and how to improve it? Is there anyway to check the quality of the mesh before starting the simulation???
I will also attach the mfREFINEMESH-LUN+FSW+FRUSTum.mfx (14.3 KB) x file!