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July 31, 2015, 08:40 |
VOF Modelling
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#1 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
Hello!!
I am a new Fluent user. I started working on my Master Thesis right now and it involves Fluent/CFD; I need to model a single elongated bubble (Taylor bubble) flowing within a column of stagnant liquid. I know I should use VOF model for that since I want to track the bubble advance within the liquid pipe. Someone can help me with that? How can I start implementing this problem, like boundary and initial conditions and how to introduce a single bubble in this problem? I read Fluent Tutorial and user s guide but it did not help me very much.... Thanks since then I really appreciate if you can help me with that.... |
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August 17, 2015, 08:17 |
VOF Modelling
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#2 |
New Member
kelich
Join Date: May 2013
Location: Tehran, Iran
Posts: 5
Rep Power: 13 |
Hi
in summary you have to do the following steps: 1- create your model 2- generate a good mesh (structured mesh is better) 3- setup your physical model like as unsteady, two phase, turbulence, ... 4- choose VOF model (obviously you have not mass or heat transfer) 5- choose liquid as a primary phase and air or gas as a secondary phase 6- active gravity and define gravity in the correct direction 7- initialize the problem in which the you domain will be filled by primary phase 8-** you have to patch the secondary phase (initial place of bubble) : you have to mark an adapted region (bubble initial place) in adaption form 9- run as you know these steps are the most important. if you want some more detail, I can help you. by the way see these link: http://www.aparat.com/v/QSApg http://www.aparat.com/v/3mMhf |
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August 17, 2015, 08:40 |
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#3 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
Thanks a lot, mrkelich!!!
I really aprecciate it! Actually, I made it and my main worry right now is to plot a transient chart: velocity of the bubble front versus time. Do you have any idea on how doing that without coding??? |
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August 17, 2015, 08:46 |
velocity
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#4 |
New Member
kelich
Join Date: May 2013
Location: Tehran, Iran
Posts: 5
Rep Power: 13 |
I have not fluent software in front of mine right now. I'll tell you as soon as possible.
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August 17, 2015, 08:51 |
velocity
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#5 |
New Member
kelich
Join Date: May 2013
Location: Tehran, Iran
Posts: 5
Rep Power: 13 |
the simplest but the poorest way is you create a pint almost in center of bubble at some times, read the velocity and then plot it manually. as you know the velocity is almost equal entire of bubble
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August 18, 2015, 09:11 |
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#6 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
mrkelich, how can I read the velocity at any point inside the bubble? There is any function in Fluent which can do that for me?
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August 18, 2015, 09:29 |
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#7 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
actually i need to track the bubble nose velocity, do you know how can i do that?
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August 18, 2015, 15:39 |
bubble
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#8 |
New Member
kelich
Join Date: May 2013
Location: Tehran, Iran
Posts: 5
Rep Power: 13 |
1- Go to surface (in main menu bar) and choose the Point
2- You can use the select point with mouse for visual selecting or enter the any point coordinate Draw contour (phases : phase-2 manual range 0.9-1) to capture bubble boundary and select the point by Right Mouse Click) 3- create the pint 4- finally you can read the flow parameters by plot or reports options. as I told this is the simplest and poorest way. |
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August 20, 2015, 12:56 |
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#9 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
Many thanks, man!
I have one final question and I wonder if you could help me out with this one: I am trying to set up a Taylor bubble 2D flowing within a column of stagnant liquid. Initially I have water on the top of the tube and gas below it. They are initially separated from each other. What I need to do is the following: It is necessary to disturb the interface in the 2D axisymmetric simulations in order to have a flow. The interface can be disturbed by setting the gravity in the opposite direction for a small time of period. After the interface was disturbed the gravity was set in the normal downward orientation again. Immediately thereafter a bubble was seen to move upward as the liquid was falling downward. How can I do that??? Disturbing the interface? Thank you man |
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August 22, 2015, 01:10 |
taylor
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#10 |
New Member
kelich
Join Date: May 2013
Location: Tehran, Iran
Posts: 5
Rep Power: 13 |
you have to patch your domain, liquid is on the top of the tube and gas below it at t=0., and also setup gravity in the right direction.
personally I prefer to do in 3d than ax-symmetric. send your email and I'll send you an example of Taylor bubble in 2d. |
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August 22, 2015, 06:32 |
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#11 |
New Member
Thiago
Join Date: Jul 2015
Posts: 7
Rep Power: 11 |
Yes, I did what you said. Actually I need to model it first in 2D case... I guess the problem is on which direction should I set the interface in order to dirturb it in the beginning. I know that after the interface is disturbed I set the gravity in the -y direction. But in the beginning is problem....
Anyway, my email is tsaumagomes@poli.ufrj.br I really appreciate your help!!! |
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September 5, 2015, 02:32 |
2d bubble column simulation
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#12 |
New Member
surya
Join Date: Jul 2015
Posts: 24
Rep Power: 11 |
hello sir
i would like to know how to model if we have separate inlet for gas and liquid (liquid column is not stagnant)which is flowing in same direction. |
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Tags |
bubble, liquid, mulitphase, vof modeling |
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