Error 1100, des/check_cell_movement.f:136, DMP

MFiX
#1

Hi everyone, in the case with DMP simulation(NODESI=4, NODESJ=5, NODESk=1), the error 1100 popup at the runing time of 0.15s, shown as Fig1. The particle velocity at the inlet is low, 0.25m/s. So I do not know why the particle detected in a ghost cell. Thank you for your help.
Ps: The files were uploaded.file.zip (51.5 MB)

fig1
fig1622×619 195 KB
fig2
fig2620×507 297 KB

#2

A collision is probably being missed, causing a particle to reach an extreme velocity. There are particles that miss collisions with the STL file and make it into the cylinders

image
image466×543 202 KB

#3

I increased the particle-wall normal spring coefficient to 100. This seems to stop the particles from entering the cyclinders. I also reduced the resolution of the cylinders from 50 to 30. You don’t need that many facets and MFiX likes large, nice facets.

Project file: 9-D38-chapai-4-v25-0.8.mfx (17.4 KB)

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#4

Thank you very much for your help.

#5

You want to make sure that the particle-wall spring stiffness coefficient (kn_w) is no larger than the particle-particle spring stiffness coefficient (kn). Said differently, (kn >= kn_w) is safe whereas (kn < kn_w) can cause problems. The reason is, the particle time step (dtsolid) is calculated based only on the particle-particle spring stiffness (kn). If kn < kn_w, the particle time step might be too large to correctly resolve wall collisions resulting in unphysical particle movements.

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#7

Dear sir. As your said, there will be problems if I increased kn_w only. How to solve the error1100?

#8

Hi ljneu. Have you solved the error 1100? I meet the same problem. Can you give me some help?

#9

I noticed recently that a tcoll_tmp based on the particle-wall spring stiffness is also calculated, but the line using this to update tcoll for the the solids time step calculation (dtsolid) is commented out:

image
image838×137 5.24 KB

Is there a reason for this? To me, it makes sense to use the minimum tcoll based on both the particle-wall and particle-particle stiffnesses.

#10

Julia: I don’t have an exact answer to your question, but look at check_solids_dem.f line 648 which has a similar computation, which is not commented out.


! Calculate the collision time scale.
            TCOLL_TMP = PI/SQRT(KN/MASS_EFF - &
               ((DES_ETAN(M,L)/MASS_EFF)**2)/4.d0)
            TCOLL = MIN(TCOLL_TMP, TCOLL)

I’m not sure why L682 is commented. I’ll try to find out why.

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