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Old   June 15, 2021, 05:41
Default How to use PatchBC
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Nino Minicucci
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Hello, my name is Nino and I'm working with REEF3D to simulate the scour produced by a spillway in the relative plunge pool. In this first stage, I would like to use the PatchBc to simulate an experimental setup in which the water enter the domain through an "hole" in the bottom so to raise the flow level and overtop a weir, but I didn't understood how to use the PatchBC to reach my goals.
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Old   June 17, 2021, 09:32
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with patchBC, you convert the solid ghostcells in a defined area (box, circle or line) into inflow or outflow conditions. Then you can assign different boundary condition characteristics.
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Old   June 17, 2021, 10:08
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Hi, thanks for the reply. In the simulation I've set a wall condition for all the boundaries (as you suggested in a past threadh), turn off the ioFlow and set this condition:
B 411 1 0.2
B 440 1 1 0.0 1.0 0.0 1.0
During the simulation its possible to observe a value for the Uq equals to the condition setted but the Ui remains always equal to zero. So in post-processing nothing happens in the domain.
I don't know if I missed some additional conditions or something else.
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Old   June 17, 2021, 10:53
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B 440 1 1 0 0 1 0 1 has a the following problem:

x_start =1
x_ end =0

that should be reversed.
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Old   June 17, 2021, 10:58
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Oh, my bad, I'm sorry. Can I ask you what stand for face?
Thanks
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Old   June 17, 2021, 11:32
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You can find the face definition in DIVEMesh User Guide in chapter 1.2.
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Old   June 17, 2021, 11:43
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I got it. Thanks again for the quickness in the reply and for the work you've done.
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Old   October 16, 2021, 04:01
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Quote:
Originally Posted by valgrinda View Post
B 440 1 1 0 0 1 0 1 has a the following problem:

x_start =1
x_ end =0

that should be reversed.
Hi i have the same problem with B441,I'm confused about this setup,especially in the setting of ID and face.My idea is to set a certain velocity in the water region.
My code is B441 0 0 0.0 0.0 0.0 35 0.0 0.012 0.0 0.6.
ID and face is the same thing?
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Old   October 17, 2021, 15:36
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Hi Hao Hao,

the face and ID are not the same thing. The face refers to the geometry: on which side of the cell is the patchBC? See the DIVEMesh User Guide, section 1.2, Fig. 1.1 for the definition of the faces / cell sides.

Important: the patchBC will convert a solid boundary to an inflow or outflow, so it needs to be placed on the domain boundary or at other solid boundaries.

Each individual patchBC should get its own ID. With this ID, it is possible to assign different boundary conditions to the patchBCs, see B 411 to B 422.
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Old   October 18, 2021, 22:22
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Quote:
Originally Posted by valgrinda View Post
Hi Hao Hao,

the face and ID are not the same thing. The face refers to the geometry: on which side of the cell is the patchBC? See the DIVEMesh User Guide, section 1.2, Fig. 1.1 for the definition of the faces / cell sides.

Important: the patchBC will convert a solid boundary to an inflow or outflow, so it needs to be placed on the domain boundary or at other solid boundaries.

Each individual patchBC should get its own ID. With this ID, it is possible to assign different boundary conditions to the patchBCs, see B 411 to B 422.
Hi Hans Bihs,
Thank you for your detailed explanation on how to define ID and patchBC functions. Now I have a preliminary understanding of it.
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Old   February 18, 2022, 19:58
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Hi REEF3D team,


Iím still confused about patchBC, is there any tutorial on how to use it?


Iíve made a simple case similar to a submerged drainage outfall (see attached picture). I was hoping to solve this using patchBC and CFD solver.


All faces are defined as walls in DiveMESH except top surface (symmetry plane). The patchBC is placed on the domain boundary (face 3 in reference to DiveMESH user guide).


Iím using the following command to represent the inflow:
B 210 1
B 411 1 10.0
B 441 1 3 4.0 6.0 0.0 0.0 0.0 2.0

During the simulation, Qi and Ui are equal to 0 and at the end, the water level in the domain is equal to the one initially imposed (no inflow).


What am I missing here? Is there any other parameters that need to be set?


Anyways, thanks for the work done.
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File Type: png REEF3D_patchBC_help.png (27.0 KB, 33 views)
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Old   February 23, 2022, 23:26
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Hi, just wanted to add I am also having this problem wherein if I set a PatchBC with an inflow and no outflow condition anywhere else the overall volume of water doesn't seem to change. I also hope a tutorial/reference setup would be available for this.
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Old   March 25, 2022, 05:25
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Dear Djamel and Ismael,

could you share the control files where you experience problems?

I am attaching a very simple patchBC test case.
Attached Files
File Type: txt control.txt (99 Bytes, 24 views)
File Type: txt ctrl.txt (326 Bytes, 27 views)
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Old   March 26, 2022, 05:54
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Ok, follow up on patchBC: it looks like there was a critical problem with setting the velocities on the patchBC. I have fixed this now and it will be part of the new release.
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Old   March 26, 2022, 08:53
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PatchBC is now fixed in REEF3D 22.03.
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Old   March 27, 2022, 04:19
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Quote:
Originally Posted by valgrinda View Post
Dear Djamel and Ismael,

could you share the control files where you experience problems?

I am attaching a very simple patchBC test case.

Good afternoon Prof Hans, I have attached the sample files as requested. I set the initial a solid at the same height as the initial water level and from my runs it never gets overtopped.
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File Type: txt control.txt (147 Bytes, 13 views)
File Type: txt ctrl.txt (246 Bytes, 11 views)
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Old   March 27, 2022, 04:38
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Have you tried with 22.03?
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Old   March 27, 2022, 05:11
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Quote:
Originally Posted by valgrinda View Post
PatchBC is now fixed in REEF3D 22.03.
Oops, sorry for the late reply; I had the page loaded up before your post. I will test it out on the latest release.
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Old   March 27, 2022, 12:27
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Quote:
Originally Posted by valgrinda View Post
Have you tried with 22.03?
Good evening Prof Hans, I believe the 411 and 442 works now thank you! The water is now overtopping the obstruction I placed properly. I will try the other PatchBC's later.

I have attached the difference in results as two images.
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File Type: jpg RECENT VERSION.JPG (40.1 KB, 33 views)
File Type: jpg Older Version.jpg (29.2 KB, 26 views)
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Old   March 27, 2022, 16:06
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Great to hear! Thanks for the feedback!
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