[vinerm]

Are you talking about the first paper you mentioned, by Ofei and Ismail? That's a fairly simple work. Are you sure you are using correct geometry for the flow rates mentioned. Secondly, you need to ensure that mesh is not fine but coarse enough that it is always larger than the largest particle size. Secondly, they have applied free-slip for the granular phase. Otherwise, the simulation is straightforward.

[minzhang]

Are you talking about the first paper you mentioned, by Ofei and Ismail? That's a fairly simple work.
Yes.

Are you sure you are using correct geometry for the flow rates mentioned.
I think so.

Secondly, you need to ensure that mesh is not fine but coarse enough that it is always larger than the largest particle size.
I think my mesh is fine.
I checked the Details of "Mesh", I only found "Minimum Edge Length" = 0.32358m. My particle size is 270microns=0.00027m.
In addition, when I did the meshing, I used "Inflation" and "Body sizing". For Body sizing, I put the element size 0.0081m. For details, please see the attachment.

Secondly, they have applied free-slip for the granular phase.
Yes. I used the free-slip wall condition boundary for the granular phase.
I chose "Specified Shear" and put all the components of Shear Stress zero.

Thanks again for all your help!! Very appreciated!!

[vinerm]

Try with a coarser mesh first. Minimum edge length is the smallest length in your geometric model. It has got nothing to do with the mesh. This is only an information provided by the Meshing tool so that user knows the smallest size of the edge and uses a mesh size smaller than that. Do NOT use a very fine mesh. A coarser has better chance of convergence.

[minzhang]

Except for my settings in both "Inflation" and "Body Sizing", I did not find any info on my mesh size statistics, such as, Max./Min. face area, Max./Min. cell volume, Max./Min. cell edge length.

Thanks!

[vinerm]

That information can be checked within Fluent. Just click on Mesh Check or issue command

me ch

This will list maximum and minimum volume. Similarly, Mesh Quality in Fluent will report minimum OQ and maximum AR.

[minzhang]

Hello vinerm,

Thanks all your help!!

As you said, it is converging with a coarser mesh. Please see the attachments.
I am using a very small deltaT = 1e-5s. So it will take quite long to finish.
After it finishes the run, I will check the results to see whether it makes sense.

So it means that my settings should be fine, right?

Then, if I want to use a fine mesh, I need to use a much smaller time step?

Originally Posted by vinerm

Try with a coarser mesh first. Minimum edge length is the smallest length in your geometric model. It has got nothing to do with the mesh. This is only an information provided by the Meshing tool so that user knows the smallest size of the edge and uses a mesh size smaller than that. Do NOT use a very fine mesh. A coarser has better chance of convergence.

[vinerm]

Mesh is about discretization in the space and time-step is about discretization in time. If the spatial discretization is fine, so should be the temporal one. So, if you use fine mesh in space, you would require fine mesh in time as well, i.e., a smaller time-step.