Strange Folders After Running Hopper-Tutorial

SimonStar · May 28, 2020, 05:42

Hello,

this is maybe a stupid question but I do not understand why my folders are so strange after running the hopper-tutorial (Particle simulation with icoUncoupledKinematicParcelFoam) with slightly changed settings.

Its creating according to the controlDict 625 normal folders within the simulated time of one second. The names are 0.0016, 0.0032, 0.048, ..., 1.

Until here its fine. But if I'm opening Paraview, it becomes strange: By pressing the Play-Button the particles are not moving but there is gravity!

Than is playing another 625 VTK-Files with the names: 1, 2, 3, ..., 625. The particles are moving now with gravity.

But for me it seems like some files are overwriting other files because the particles were already falling down half way at the first step (Picture).
The start positions are not fitting with the positions in the cinematicCloudPosition file.

PicPost.PNG

Can someone pls explain me whats going on here?
Do I need those Files?

Thank you a lot - also for suggestions and partly help.

Thank you
Simon

HPE · May 28, 2020, 18:39

Hi,

- Might I didn't understand ur question, if so my apologies: the time intervals that you think the particles do not move is less than a second - on order of O(-4) seconds {0.9995, 0.9996, 0.9997 ...}.
- Then the time intervals became of an order of a second {1, 2, 3...} , and you see the particles are moving, which is viable.
- Could you please clarify ur question, if I am missing smt.

SimonStar · June 2, 2020, 02:55

Hello HPE,

thank you a lot for your reply. In general you understood it right but sorry if the question was written not good enough. I will clarify it.

My geometry is a cube with only 5cm length. Right now I just have gravity (other forces will follow when this case is fine). After one second (with 625 written Intervals) you should see a movement of the particles but when I am jumping within that second (e. g. first to last step) There is no movement.

Somehow in Paraview are those other files with the one-second-step. Here you can see the particles moving from time 1 s to 625 s. The thing is that I never defined those steps in the controlDict.

My suggestion right now is that those files are just copies with different names from the files with the short time step. Because in my case the particles can not fall for more than 10 minutes (625 s) downwards. Maybe it has something to do with the fix from 'Wildcad' to read the VTK-files in paraview? Writing the old 'positions' file in Lagrangian solvers as of OpenFOAM 5.x

Otherwise I don't have a clue why this is happening Also not why the particles are fallen down already half way in the first timestep. They were randomly distributed. You can see some of them already at the bottom.

I hope this helps
Thank you Simon

May 28, 2020, 05:42	Strange Folders After Running Hopper-Tutorial	#1
SimonStar Member Simon Join Date: Sep 2019 Location: Germany Posts: 51 Rep Power: 7	Hello, this is maybe a stupid question but I do not understand why my folders are so strange after running the hopper-tutorial (Particle simulation with icoUncoupledKinematicParcelFoam) with slightly changed settings. Its creating according to the controlDict 625 normal folders within the simulated time of one second. The names are 0.0016, 0.0032, 0.048, ..., 1. Until here its fine. But if I'm opening Paraview, it becomes strange: By pressing the Play-Button the particles are not moving but there is gravity! Than is playing another 625 VTK-Files with the names: 1, 2, 3, ..., 625. The particles are moving now with gravity. But for me it seems like some files are overwriting other files because the particles were already falling down half way at the first step (Picture). The start positions are not fitting with the positions in the cinematicCloudPosition file. PicPost.PNG Can someone pls explain me whats going on here? Do I need those Files? Thank you a lot - also for suggestions and partly help. Thank you Simon

May 28, 2020, 18:39		#2
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 931 Rep Power: 13	Hi, - Might I didn't understand ur question, if so my apologies: the time intervals that you think the particles do not move is less than a second - on order of O(-4) seconds {0.9995, 0.9996, 0.9997 ...}. - Then the time intervals became of an order of a second {1, 2, 3...} , and you see the particles are moving, which is viable. - Could you please clarify ur question, if I am missing smt. __________________ The OpenFOAM community is the biggest contributor to OpenFOAM: User guide/Wiki-1/Wiki-2/Code guide/Code Wiki/Journal Nilsson/Guerrero/Holzinger/Holzmann/Nagy/Santos/Nozaki/Jasak/Primer Governance Bugs/Features: OpenFOAM (ESI-OpenCFD-Trademark) Bugs/Features: FOAM-Extend (Wikki-FSB) Bugs: OpenFOAM.org How to create a MWE New: Forkable OpenFOAM mirror

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June 2, 2020, 02:55		#3
SimonStar Member Simon Join Date: Sep 2019 Location: Germany Posts: 51 Rep Power: 7	Hello HPE, thank you a lot for your reply. In general you understood it right but sorry if the question was written not good enough. I will clarify it. My geometry is a cube with only 5cm length. Right now I just have gravity (other forces will follow when this case is fine). After one second (with 625 written Intervals) you should see a movement of the particles but when I am jumping within that second (e. g. first to last step) There is no movement. Somehow in Paraview are those other files with the one-second-step. Here you can see the particles moving from time 1 s to 625 s. The thing is that I never defined those steps in the controlDict. My suggestion right now is that those files are just copies with different names from the files with the short time step. Because in my case the particles can not fall for more than 10 minutes (625 s) downwards. Maybe it has something to do with the fix from 'Wildcad' to read the VTK-files in paraview? Writing the old 'positions' file in Lagrangian solvers as of OpenFOAM 5.x Otherwise I don't have a clue why this is happening Also not why the particles are fallen down already half way in the first timestep. They were randomly distributed. You can see some of them already at the bottom. I hope this helps Thank you Simon