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Timestep synchronization between CFD_VTU and 6DOF_VTP groups

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Old   February 8, 2024, 08:00
Default Timestep synchronization between CFD_VTU and 6DOF_VTP groups
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Stamatios Petalas
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Hello,

I have the following problem during my testing:

I successfully run a configuration with a numerical wave tank, which has walls in all faces except the wave generation one. An .stl file was used to import a floating body, and the simulation run smoothly. The ctrl.txt file can be seen below.

When I import the pvtu group in paraview I realize that the time-steping is different from the vtp file that describes the floating object, so the two are out of sync during the animation.

I know that I can use a time synchronization filter in paraview to match the two, but my question is: how can I change this within the input file, so that data are written at the same timesteps?

Best,
Stamatis
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Old   February 8, 2024, 16:29
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Ahmet Soydan
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I can not see your ctrl file. Can you share it ?

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Originally Posted by pe_sta View Post
Hello,

I have the following problem during my testing:

I successfully run a configuration with a numerical wave tank, which has walls in all faces except the wave generation one. An .stl file was used to import a floating body, and the simulation run smoothly. The ctrl.txt file can be seen below.

When I import the pvtu group in paraview I realize that the time-steping is different from the vtp file that describes the floating object, so the two are out of sync during the animation.

I know that I can use a time synchronization filter in paraview to match the two, but my question is: how can I change this within the input file, so that data are written at the same timesteps?

Best,
Stamatis
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Old   February 9, 2024, 05:52
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Stamatios Petalas
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Yes, sorry, I forgot to attach the file. Here it is.
Stam
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File Type: txt ctrl.txt (2.0 KB, 7 views)
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Old   February 9, 2024, 06:17
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Ahmet Soydan
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VTU and VTP printout files are supposed to be sync. Which version of REEF3D are you using?
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Yes, sorry, I forgot to attach the file. Here it is.
Stam
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Old   February 10, 2024, 02:50
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Stamatios Petalas
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Thank you Ahmet. I'm using version 23.11, so I guess this shouldn't be the problem..

In my case, the run has created 165 VTU files and 440 VTP files; I cannot find a logic relation between the two numbers.

Is there a way to force printout synchronization, or maybe manually set the time-step of VTP printout?
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Old   February 10, 2024, 03:50
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Felix S.
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Hey,


I think this is a bug related to P20 and P35. In all 6DOF files, there is a print flag:

Code:
if(((p->count%p->P20==0) && p->P30<0.0)  || (p->simtime>printtime && p->P30>0.0)   || (p->count==0 && p->P35==0))
P20 is initialized to be -10 if nothing else is given. Therefore, the printer prints for your P35 option AND for p->count%p->P20==0 so every tenth iteration.

I will forward this to the bug report channel, so there is a quick fix

For your application, why don't you use P 30 0.05 for the time being? Should result in the output you want.

Kind regards
Felix
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Old   February 10, 2024, 07:19
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Stamatios Petalas
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This was very insightful Felix and good to know, thanks a lot.

Following your suggestion the synchronization problem was solved; VTU and VTP files are now printed at the same timestep.

Best,
Stamatis
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