Hello,
I hope you are doing well.
Can anyone please tell me the format for the particle_input.dat for the glued sphere particle(MFiX-GSP) model? Or how can I modify the particle_input.dat file of SQP that I am using currently(which I am attaching here-
particle_input.dat (80.7 KB)
I am looking forward to hearing from you soon.
Sincerely,
Sumanth Penmetcha
Hello,
Please see the following for a template of the particle_input.dat for the GSP model.
particle_input.dat (4.0 KB)
A few things need to be noted for this:
The number of glued particles needs to be given by "NGluedParticles = " in the *mfx file. Unfortunately, it has not been added to GUI yet. You may need to change it in the file directly. We will add it to GUI in the future release.
The number of component spheres needs to be given by "Particles = " in the *mfx file. You can modify it through GUI.
In the particle_input.dat file, the total number of spheres is given by "TotalComponentSpheres: ". The data, including x,y,z, density, diameter et al, are for glued particles.
For example, I want to have 20 glued particles and each glued particle has 18 component spheres. I will set " “NGluedParticles = 20” and “Particles = 360” in the *mfx file. In the particle_input.dat file, I will set “TotalComponentSpheres: 360” and add the parameters for each glued particle in the file, which gives me a total of 55 lines in the file.
Hello,
Thank you for your response.
May I please know what is the bounding_diameter in the particle_input.dat file that you have given me?
Since the particles are like super small, than I expect. That would be super helpful to me.
Also as I am running the simulation, I am getting the following error-
[Himas-MacBook-Pro.local:08757] shmem: mmap: an error occurred while determining whether or not /var/folders/rj/b7mxhr792v57bq380b_kjd6w0000gp/T//ompi.Himas-MacBook-Pro.502/jf.0/513409024/sm_segment.Himas-MacBook-Pro.502.1e9a0000.0 could be created.
But the simulation is running. I am not sure what’s happening with that error.
Please let me know if you want me to provide more information to help solving the issue.
I am looking forward to hearing from you soon.
Sincerely,
Sumanth Penmetcha
The bounding_diameter is the bounding diameter of the glued particles you used in your case. You need to set it based on your case.
The error does not seem to be related to MFiX. Please try to check the simulation results considering it is running.
If you need further help, please provide the particle_input.dat file and the case file you use.
Thank you for your response.
So, If I would have to calculate the terminal velocities for each of the glued particles, I need the diameter of each component sphere(all 4752 spheres in my case) that is forming can you please let me know how may I approach this problem?
Any suggestions would be highly helpful for calculating the terminal velocities of each of the 528 GSP particles.
Also Please find the attachment for particle_input.dat file and GSP Case file.
GSP_528 copy.zip (611.6 KB)
An update: For now I have calculated a set of terminal velocities, but I am getting an error, which says,
Error from des/desgrid_mod.f:1028
Error: There exists a NORMAL particle in a GHOST cell.
Particle may have gone OUT-OF-BOUNDS.
To resolve this issue, please consider:
a) Verify all wall boundary conditions are defined
b) Reducing the value of the variable NEIGHBOR_SEARCH_N (Solids>DEM>Max steps between neighbor search)
c) Increasing the particle and/or wall stiffness (Solids>DEM>Normal spring constant or Young’s modulus)
Current particle location (x, y, z coordinates): 0.3898E-01, -0.2438E-03, 0.4038
Current particle velocity (u, v, w components) : -3.937 , -46.51 , -3.680
I was wondering if there’s a way we can know about or narrow down the particle which is going out of bounds.
Please let me know how can I mitigate this error.
Please find the attachment for the updated case file zip.
GSP_528 copy 2.zip (593.4 KB)
I am looking forward to hearing from you soon.
Thank you.
Sincerely,
Sumanth Penmetcha
Hi Sumanth,
So for your case, you can change kn and kn_w to 2.5e6, you might also want to change neighbor_search_n to a smaller number, like 20. The reason is that you have gsp particles in different size and some of them have very large initial velocities, you have to either decrease solid time step or increase contact stiffness.
Hello Renjie,
Thank you so much for your responses.
I will definitely consider your suggestions and work on it.
I hope you have a great rest of your day!
Thanks again,
Sumanth
Hello Renjie,
The problem persists, with my case, I am attaching the case file in here, please let me know if there are other ways to resolve this issue. I have tried reducing the velocities, increasing kn and kn_w and decreasing the solid time step.
Thank you so much for your time.
revised_0826_GSP_528 2.zip (816.1 KB)
