It turns out your STL file is not clean. There are many duplicate vertices/triangles. Please see attached. My recommendation is you start with much simpler models to get familiar with the procedure. See 3. Tutorials — MFiX 21.3 documentation for some examples. For non-rectangular geometries, the cut-cell method is the only option. To clean your STL file, use the CAD sofware you used to generate the file, it should have options to remove duplicates and recompute normals.
What worries me in your simulation is that the inlet velocity is quite high (around 9 m/s) for the size of the inlet tube (around 2.5 mm), and you have many other tubes smaller than 1 mm, so you will end up with very large velocities that require tiny time steps (see picture below). In the attached, I used a grid spacing that will get you the bare minimum to resolve the internal tubes, and I had to use fairly large values of the snap and small cell tolerances to get it to run (you may be able to find a better combination that work too). I also removed duplicates in the stl file, which went from 2894 triangles to 1298. It still has many stretched triangles, and you need to set a facet angle tolerance to zero or close to zero so no facet is excluded. You want to see this
Total number of facets read = 1298
Number of valid facets = 1298
Number of ignored facets = 0
If you have ignored facets, this will create holes in the stl and the meshing will likely fail.
Thank you Jeff, but when I load your updated .mfx and .stl, the “index, dimension 1, above upper bounds” type error happened again, and I did not change your settings and the .stl file. So I wonder whether there exists some stochastic effects to incur error in one computer while run meshing normally in another computer? Thank you.
And when I just copied and pasted your clean .mfx and .stl files into a new project and open the project by clicking its .mfx file, the error reported in the following link happened. I remembered this kind of problem happened just after I deleted the mfix21.2 and installed 21.3 version. And there is no bug report generated currently. Thank you.
Thank you Jeff, I tested the files you attached above, and the “index, dimension 1, above upper bounds” type error as follows is persistent. I want to know whether the above attached project modified by you can successfully run in your computers. Thank you.
And another question referring to the following quote is that if the reason for the quoted problem is unclean .stl file, why the “index, dimension 1, above upper bounds” type error still appeared when I replaced the origin .stl with the clean one uploaded. Thank you.
And could you please recommend me a software to remove the duplicate entities including facets, vortexs and lines? Since I can not find the tools and commands in solidworks to do the above job and flip their norm (if you know, could you please tell me)? It would be better if it is open-sourced. Thank you.
Hey Jeff, I hope I am not bothering you too frequently, I am willing to know whether you have any updates for the problem I have posted. Now that you have posted the gas velocity distribution across the chamber, could you please tell me how long you have simulated in that case and can you give me the evolution of bulk density, volume fraction and outlet mass flowrate as well? Thank you for your consideration. I need your help.
We have a potential fix for the meshing issue on Windows that we will make available in the next few days (21.3.1 point release). Even if you can mesh, it will take too long to run on a PC, you will need access to a cluster. I only ran for 0.1s to troubleshoot and I did not analyze any data.
Ju Wu - please understand that we all have full-time jobs and MFiX support is provided on a best-effort basis. We are all working on our own research and development of MFiX. Please be patient when asking questions on the forum and do not repeat the same questions in different threads. Thanks.
I am personally using Blender right now, but I have used meshlab in the past. I don’t know about solidswork, but I imagine they have some clean up tools.
Thank you Jeff, could you please explain why this type of problem happened only under WINDOWS? Now that I found out that the the installation and create-environment command under WINDOWS and LINUX are the same, so I assume they create and install the same software under Anaconda. Thank you.
Here each slice is saved in a different vtu file, and the two files are loaded in Paraview. If your vtk region is set as a plane, it will save a slice (on cell thick).
You can also do the slicing in Paraview if you have the full 3D domain in the vtu file.
Thank you Jeff, as you said you only simulate 0.1s, can you tell me your settings for computing cluster such as the node number, the cores, the task-per-core and so on? And I wonder whether the project you attached finally converged or not since I found our defects/holes in the generated mesh by your .mfx and .stl files. Thank you in advance for your answers.
I used 4 nodes, 40 cores per node, so a total of 160 cores. I can’t say if this would eventually run to completion . I know you had some pretty high velocities so it is possible it would fail at some point.
Hi Jeff, I have imported the same .stl file to the blender 2.9, there are two functions one is “merge vortex” and the other is “clean up” under “modeling” bar “mesh” subbar. But it shows that 0 vortex removed. So could you please tell me which method I can use in Blender to detect the double faces, vortex automatically and remove them then? Thank you in advance.
I used an older version (2.79) that has a “remove double” option. Maybe the equivalent for 2.9 is Mesh>cleanup>merge by distance. You may need to adjust the merge distance and make sure all faces/vertices are selected.
