2phase outlet boundary condition #24
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This is due to the use of periodic on the right hand side. Because the
right BC's neighbour becomes the left BC which is a fixed color... So you
can use fixed color for both left and right, this should help to solve the
problem.
…On Thu, 25 Jan 2024 at 12:03, emwn123 ***@***.***> wrote:
Hello Dr. Yang, I have questions about the color-gradient multiphase
model. For the phase boundary, you showed in the example that the left side
is the fixed phase1 boundary (value=-1) and the right side is the periodic
boundary. When calculating, I found that, The value of phase1 will also run
to the right. So I want to know what is the reason for this?
756b968a4ca5366172a89fe3fa2856e.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/6b1cff7f-3dad-4687-8c79-edf7de7635f9>
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/985edbba-2aed-4d2b-9e08-390edc2017b1>
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Thanks for the fast reply! I used the fixed BC as you said, but the problem remains. Did I misunderstand what you said?
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The second line of phase boundary you need to use 1 1.0 not 1 -1.0, 1.0
represent red phase, -1.0 represents blue phase
…On Thu, 25 Jan 2024 at 12:18, emwn123 ***@***.***> wrote:
Thanks for the fast reply!
I used the fixed BC as you said, but the problem remains.
Did I misunderstand what you said?
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/34d17754-1a0b-4c7e-aaa9-939fde3fc5ca>
image.png (view on web)
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Thanks for the reply. Now it worked! But there is a new problem, that is, the blue phase will not continue to displace the red phase after a certain time step, and will always remain in the state shown in the figure below. What could be the reason for this?
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Maybe you need bigger driving force, I would suggest using periodic and
body force to drive the fluid instead of using fix velocity/pressure BC
…On Thu, 25 Jan 2024 at 13:45, emwn123 ***@***.***> wrote:
Thanks for the reply.
Now it worked!
But there is a new problem, that is, the blue phase will not continue to
displace the red phase after a certain time step, and will always remain in
the state shown in the figure below. What could be the reason for this?
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/3df5baa2-02cb-42ab-8e65-b7b480bc84ce>
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I see. Thanks for the fast reply and the nice code! |
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Hello Dr. Yang If I want to simulate as shown below, how should I set the body force or velocity in the y-axis direction? It seems that the body force at the upper inlet and lower inlet of the y-axis are not in the same direction. I tried velocity BC and that doesn't seem quite right either. Can you give me some advice?
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You want to inject fluid from three inlets?
It's not an easy case for bodyforce, I think you can only use velocity BC
for three inlets and constant pressure BC for outlet.
emwn123 ***@***.***> 于 2024年1月25日周四 下午4:13写道：
… Hello Dr. Yang
If I want to simulate as shown below, how should I set the body force or
velocity in the y-axis direction? It seems that the body force at the upper
inlet and lower inlet of the y-axis are not in the same direction. I tried
velocity BC and that doesn't seem quite right either. Can you give me some
advice?
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/4f3f8e5f-c120-4e57-a5d5-26ffd9e8404c>
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Yes. So in the y-axis direction I should set the opposite, right? For example, one side is Vy and the other side is -Vy |
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correct!
…On Thu, 25 Jan 2024 at 17:11, emwn123 ***@***.***> wrote:
Yes.
So in the y-axis direction I should set the opposite, right? For example,
one side is Vy and the other side is -Vy
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Hi Dr. Yang, Sorry to bother you again. Based on your suggestion, I set the velocity BCs on the three inlets, but it doesn’t seem to be very effective. No matter how I change the velocity, the phase at the left inlet always gets stuck after a certain time step.
It would be very grateful if you give me some guidance. |
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Maybe you need to change bc_x_right into 1, 0.99, 0.0, 0.0 ,0.0 ?
…On Thu, 25 Jan 2024 at 23:34, emwn123 ***@***.***> wrote:
Hi Dr. Yang,
Sorry to bother you again.
Based on your suggestion, I set the velocity BCs on the three inlets, but
it doesn’t seem to be very effective.
No matter how I change the velocity, the phase at the left inlet always
gets stuck after a certain time step.
(If a body force in the x direction is applied on this basis, the phase
will continue to drive smoothly. But this is wrong, because the two inlets
in the z-axis direction will also be affected.)
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/fdfda826-ce66-4571-93b3-6bd0e2b1d92d>
The following are the specific settings and post-processing results:
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/438acdb7-41b9-49a9-9e7b-56078fab24c1>
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/854172ae-c1bc-4846-a246-32c0ac3d2de4>
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/1fbd0b59-0b51-4dfc-a4b5-ae92b4ca9ed4>
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/ebbb7fe5-f9fb-4711-bf8e-ecca097ac68e>
image.png (view on web)
<https://github.com/yjhp1016/taichi_LBM3D/assets/63047567/792c10b9-069f-42b7-a678-1eadc1a0ae1d>
It would be very grateful if you give me some guidance.
Thanks a lot!
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Hello Dr. Yang, I have questions about the color-gradient multiphase model. For the phase boundary, you showed in the example that the left side is the fixed phase1 boundary (value=-1) and the right side is the periodic boundary. When calculating, I found that, The value of phase1 will also run to the right. So I want to know what is the reason for this?
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