CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Pre-Processing

flow over cylinder

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

Like Tree1Likes
  • 1 Post By Tobi

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 11, 2016, 19:04
Default flow over cylinder
  #1
New Member
 
jafar
Join Date: Jul 2014
Posts: 16
Rep Power: 10
bagherij is on a distinguished road
Hi
i am working on flow past cylinder with Re=0 ,i attached geometry .there are no require set pressure boundary at AB and BC ,how can i implement it in 0/p?i set it as below but no working fine.please help


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];

internalField uniform 1;

boundaryField
{
left
{
type symmetryPlane;
}

right
{
type fixedValue;
value uniform 0;
}

down
{
type symmetryPlane;
}

up
{
type zeroGradient;
}

cylinder
{
type zeroGradient;
}

frontAndBack
{
type empty;
}
}


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class volVectorField;
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
left
{
type symmetryPlane;

}

right
{

type fixedValue;
value uniform (0 1 0);
}

down
{
type symmetryPlane;

}

up
{
type fixedValue;
value uniform (0 1 0);
}

cylinder
{
type fixedValue;
value uniform (0 0 0);
}

frontAndBack
{
type empty;
}
}

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.2.2 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver GAMG;
tolerance 1e-6;
relTol 0;
smoother GaussSeidel;
nPreSweeps 2;
nPostSweeps 2;
cacheAgglomeration on;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 10;
mergeLevels 1;
}

U
{
solver smoothSolver;
tolerance 1e-6;
relTol 0;
smoother GaussSeidel;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;
pRefPoint (2,0,0);
pRefCell 0;

residualControl
{
p 1e-3;
U 1e-4;
}
}

relaxationFactors
{
fields
{
p 0.3;
}
equations
{
U 0.7;
}
}
Attached Images
File Type: png square.png (27.7 KB, 5 views)

Last edited by bagherij; August 12, 2016 at 11:12.
bagherij is offline   Reply With Quote

Old   August 12, 2016, 08:35
Default
  #2
Member
 
Join Date: Feb 2015
Posts: 39
Rep Power: 9
HenningW is on a distinguished road
Hi,

I am not sure what you mean by Re=0. So there is no flow at all?

Can please provide an error message or what exactly is not working?
HenningW is offline   Reply With Quote

Old   August 12, 2016, 08:45
Default
  #3
Member
 
Join Date: Feb 2015
Posts: 39
Rep Power: 9
HenningW is on a distinguished road
On the right hand side you have a symmetry wall, yet you want a flow perpendicular to it? I do not think thats physically possible. Correct me if I am wrong, by in a symmetry plane the mass-flow should be 0 and thus the stream lines need to parallel to the surface, otherwise you have a line with mass constantly flowing in from both sides. Where is the fluid supposed to go without removing mass or compressing it to infinity?
HenningW is offline   Reply With Quote

Old   August 12, 2016, 11:47
Default
  #4
New Member
 
jafar
Join Date: Jul 2014
Posts: 16
Rep Power: 10
bagherij is on a distinguished road
Dear
there was some mistake in the picture,i changed it.
the flow is non-newtonnian (creeping flow like foams , filled polymer solution ) therefore re<<1, i attached the governing equations .the problem considered with two planes of symmetry, hence one quater of the domain is used,also i attached the all domain.
Thanks
Attached Images
File Type: png governing-.png (51.3 KB, 10 views)
File Type: png all domain.png (65.3 KB, 12 views)
bagherij is offline   Reply With Quote

Old   August 13, 2016, 04:50
Default
  #5
Super Moderator
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Tussenhausen
Posts: 2,661
Blog Entries: 6
Rep Power: 48
Tobi has a spectacular aura aboutTobi has a spectacular aura aboutTobi has a spectacular aura about
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
Hi all,

  • first I did not check you first post because there are missing code-tags.
  • out of the last post, you have to implement a few stuff yourself.
  • I am not sure if eqn. 9 and 10 are correct (you should derive this yourself to be sure).
  • If the viscosity model is not implemented in foam, you have to implement it yourself.
  • based on your domain, you need to set the pRefValue in fvSolutions. Otherwise it will not work because you are not defining a well constrained problem.


Finally it is exact that one here: http://www.holzmann-cfd.de/index.php...gelumstroemung
But in your case it is a non-newtonian flow. Based on the tensors and fluid behaviors, maybe you are allowed to simplify the deviatoric stress tensor to get a Poisson equation but maybe it is not possible. Anyway (:
bagherij likes this.
__________________
Keep foaming,
Tobias Holzmann
Tobi is offline   Reply With Quote

Old   August 13, 2016, 16:59
Default
  #6
New Member
 
jafar
Join Date: Jul 2014
Posts: 16
Rep Power: 10
bagherij is on a distinguished road
Dear Tobi
I attach the domain ,I dont want to apply pressure boundary condition at AB(up) and BC (right) ,how can i do it in the codes?

object p;

boundaryField
{
left
{
type symmetryPlane;
}

right
{
?????????????what should i write???
}

up
{
?????????????what should i write???
}
.
...
Attached Images
File Type: png square.png (27.7 KB, 4 views)
bagherij is offline   Reply With Quote

Old   August 13, 2016, 17:28
Default
  #7
Super Moderator
 
Tobi's Avatar
 
Tobias Holzmann
Join Date: Oct 2010
Location: Tussenhausen
Posts: 2,661
Blog Entries: 6
Rep Power: 48
Tobi has a spectacular aura aboutTobi has a spectacular aura aboutTobi has a spectacular aura about
Send a message via ICQ to Tobi Send a message via Skype™ to Tobi
First guess,
  • right -> p :: zeroGradient
  • up -> p :: zeroGradient
set the refPressure close to the symmetry point and try.

PS: I am not sure if you can simplify the case in that way. It should be wrong if I think about it. You should have 2 symmetryPlanes but could it be that you have 3. ?
__________________
Keep foaming,
Tobias Holzmann
Tobi is offline   Reply With Quote

Reply

Tags
openfoam 2.1, pressure boundary, velocity boundary

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
Drag force coefficient too low for a flow past cylinder at Re= 1e05 Scabbard STAR-CCM+ 2 June 5, 2020 14:44
Flow past a cylinder at Re 1e05 using LES, drag force coefficient is to low Scabbard Main CFD Forum 21 June 19, 2018 13:58
Flow around cylinder free to rotate Jonas Holdeman Main CFD Forum 5 August 3, 2015 17:54
benchmark: flow over a circular cylinder goodegg Main CFD Forum 12 January 22, 2013 11:47
Flow over a cylinder Anna Main CFD Forum 9 March 24, 2006 14:32


All times are GMT -4. The time now is 14:05.