CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Boundary Conditions. Simulation cylinder.

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree1Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 8, 2010, 14:26
Smile Boundary Conditions. Simulation cylinder.
  #1
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Hello! I just started with OpenFOAM.
I use version 1.7.0. I'm trying to simulate a cylinder in which the laminar (or turbulent) incompressible fluid flow.
And the bottom of the cylinder rotates. Like this:



What is the boundary condition I set on the bottom and how to do it?
I would be grateful for any assistance conditional. Maybe someone has already done this?
Sorry for my English

A! And what solver shall i use?
davidmd is offline   Reply With Quote

Old   September 11, 2010, 13:30
Default
  #2
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Surely no one can help? It's very, very important to me, please...
davidmd is offline   Reply With Quote

Old   September 17, 2010, 09:42
Default
  #3
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 23
maddalena will become famous soon enough
Hi David and welcome! Hope to be not too late...
Quote:
Originally Posted by davidmd View Post
what solver shall i use?
Everything depends on what simulation you want to perform. I guess you want a steady state laminar or turbulent simulation. In that case I would use simpleFoam.
Quote:
Originally Posted by davidmd View Post
And the bottom of the cylinder rotates. What is the boundary condition I set on the bottom and how to do it?
If you wants that the cylinder bottom is the only rotating surface, than I would apply a rotatingWall BC. Search in the forum for the way to apply it.
Enjoy

mad
sharonyue likes this.
maddalena is offline   Reply With Quote

Old   September 19, 2010, 11:04
Default
  #4
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Thank you very much, maddalena, I built something like the geometry and boundary conditions, but I used iсoFoam not simpleFoam. What is the difference between them?
I apologize for maybe a stupid question. I just sooo hard to read literature in English
davidmd is offline   Reply With Quote

Old   September 20, 2010, 04:01
Default simpleFoam v.s. icoFoam
  #5
ata
Senior Member
 
ata's Avatar
 
ata kamyabi
Join Date: Aug 2009
Location: Kerman
Posts: 323
Rep Power: 17
ata is on a distinguished road
Hi David
How are you? I hope you are doing very well.
As you can see in the source of the solvers icoFoam is a transient solver for incompressible, laminar flow of Newtonian fluids and simpleFoam is a steady-state solver for incompressible, turbulent flow.
Good luck
Best regards

Ata
ata is offline   Reply With Quote

Old   September 23, 2010, 09:42
Default
  #6
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Now I'm faced with this problem. I can not define the boundary condition at the upper edge of the cylinder (i mean the top sureface of my fluid). Maybe someone knows how to do this? Uz = 0, dUx / dx = 0, dUy / dy = 0

Last edited by davidmd; September 23, 2010 at 10:16.
davidmd is offline   Reply With Quote

Old   September 23, 2010, 09:47
Default
  #7
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Hi, ata!
Thank you for help, I hope you are all well too!
davidmd
davidmd is offline   Reply With Quote

Old   September 23, 2010, 11:14
Default
  #8
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
I'm trying to simulate simple mixer. It looks like cylinder with rotating bottom and open top filled with fluid. The other cylinder is inserted into the first.
So something like this:








So, on the walls of this cylinders i set the fixedValue BC On the bottom - rotatingWallVelocity.
And to top I want to set the boundary condition such as on the surface of the liquid ... At first I tried to do zeroGradient boundary condition. But then it turns out like this:


It turns out that the fluid enters the center and comes out at the edges, but this is not correct.
I thought that it was possible to establish a boundary condition like Uz = 0 Ux = dUx / dx Uy = dUy / dy

Maybe i need another BC... I don't know. The main thing that it was just on the surface of the liquid.

Once again: sorry for my English :-)
davidmd is offline   Reply With Quote

Old   September 23, 2010, 11:48
Default
  #9
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 23
maddalena will become famous soon enough
Mmm...
I am still confused by your geometry...
there are two cylinders, one inside the other, filled with fluid. The external one has a rotatingWall BC, while the internal one is fixed. The bottom of the internal cylinder is open. You want to study the effect of the bottom surface rotation of the external cylinder into the fluid. Am I right?
What about your pressure BC?
As a first idea, I would use an inletOutlet BC for U and a fixedValue for p. But not sure about that.

mad
maddalena is offline   Reply With Quote

Old   September 23, 2010, 15:34
Default
  #10
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
maddalena, you are right!
My preasure BC is set to fixedValue and it is 0...
davidmd is offline   Reply With Quote

Old   September 23, 2010, 16:16
Default
  #11
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 23
maddalena will become famous soon enough
So, this is fine:
Quote:
Originally Posted by davidmd View Post
My preasure BC is set to fixedValue and it is 0...
if you fix pressure, you cannot fix velocity, and your gradient should be specified instead. I would use an inletOutlet with an inletValue (0 0 0): it will behave as a fixedValue on the inner cylinder and as a zeroGradient on the fluid between the two cylinder.
what you think about that?

mad
maddalena is offline   Reply With Quote

Old   September 24, 2010, 04:33
Default
  #12
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
You mean the boundary condition inletOutlet with inletValue (0 0 0) on the upper surface of the cylinder?
davidmd is offline   Reply With Quote

Old   September 24, 2010, 04:57
Default
  #13
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 23
maddalena will become famous soon enough
Quote:
Originally Posted by davidmd View Post
You mean the boundary condition inletOutlet with inletValue (0 0 0) on the upper surface of the cylinder?
Yes, that one. Please report if you have different ideas or if you can find a solution.
cheers

mad
maddalena is offline   Reply With Quote

Old   September 24, 2010, 12:52
Default
  #14
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Quote:
Originally Posted by maddalena View Post
Yes, that one. Please report if you have different ideas or if you can find a solution.
cheers

mad
Wow! It works exactly as I have! maddalena, thank you very much! It's great!!! I never would have guessed! :-)
davidmd is offline   Reply With Quote

Old   September 26, 2010, 08:44
Default
  #15
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 23
maddalena will become famous soon enough
Quote:
Originally Posted by davidmd View Post
Wow! It works exactly as I have! maddalena, thank you very much! It's great!!! I never would have guessed! :-)
That is nice! Happy to be useful!
Cheers

mad
maddalena is offline   Reply With Quote

Old   October 6, 2010, 10:42
Default cylindrical shapes
  #16
Senior Member
 
Join Date: Sep 2010
Posts: 226
Rep Power: 16
T.D. is on a distinguished road
Hi guys
since you worked with cylindrical shapes i thought you might help me please

i need to do a flow between two parallel disks the bottom is stationary and the on eon top rotates with a certain omega.

How to draw?

Help please, and what about the BCs?

thanks a lot
T.D. is offline   Reply With Quote

Old   October 6, 2010, 15:49
Default
  #17
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
Hi, T.D.!
I don't understand your geometry
maybe you can draw it?
It's very difficult to me to wrote on english
__________________
davidmd
davidmd is offline   Reply With Quote

Old   October 6, 2010, 18:15
Post Drawing attached
  #18
Senior Member
 
Join Date: Sep 2010
Posts: 226
Rep Power: 16
T.D. is on a distinguished road
hi
this is the drawing attached

thanks a lot
Attached Images
File Type: jpg flow.JPG (11.9 KB, 64 views)
T.D. is offline   Reply With Quote

Old   October 6, 2010, 19:31
Default
  #19
Member
 
David
Join Date: Aug 2010
Location: North Ossetia, Vladikavkaz
Posts: 30
Rep Power: 15
davidmd is on a distinguished road
Send a message via ICQ to davidmd
i'm not sure, but you probably should use BoundaryFOAM
And create such a geometry will be no problems. If you want me to send you an example of my case with rotating bottom. But you have to fundamentally alter it.
__________________
davidmd
davidmd is offline   Reply With Quote

Old   October 7, 2010, 03:33
Default
  #20
ata
Senior Member
 
ata's Avatar
 
ata kamyabi
Join Date: Aug 2009
Location: Kerman
Posts: 323
Rep Power: 17
ata is on a distinguished road
Hi T.D.
How are you brother? I hope you are doing very well.
May be you can use gambit for mesh generation.
Good luck
Best regards

Ata
ata is offline   Reply With Quote

Reply

Tags
boundary conditions, simulation cylinder

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
mass flow in is not equal to mass flow out saii CFX 12 March 19, 2018 06:21
[ICEM] Problem with boundary layers for cylinder in channel nik ANSYS Meshing & Geometry 0 October 27, 2009 07:01
Concentric tube heat exchanger (Air-Water) Young CFX 5 October 7, 2008 00:17
Convective Heat Transfer - Heat Exchanger Mark CFX 6 November 15, 2004 16:55
Need help about boundary conditions for a francis runner flow simulation Rodrigo Escobar Moragas Main CFD Forum 1 October 26, 1998 09:20


All times are GMT -4. The time now is 02:48.