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

The problem for velocity calculation using turbulent model in openfoam.

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

Like Tree1Likes
  • 1 Post By haakon

Reply
 
LinkBack Thread Tools Display Modes
Old   September 4, 2013, 11:18
Default The problem for velocity calculation using turbulent model in openfoam.
  #1
New Member
 
Maosong Cheng
Join Date: Aug 2012
Posts: 19
Rep Power: 3
mscheng is on a distinguished road
Hi FOAMer,

I use standard k-epsilon model to simulate the velocity of a circular tube(R=1.7m,H=4.0m), but I find the velocity near wall in the inlet become bigger than the velocity fixed in the inlet. what is wrong?

thanks!
Attached Images
File Type: jpg 1.jpg (16.2 KB, 11 views)
File Type: jpg 2.jpg (7.6 KB, 12 views)

Last edited by mscheng; September 10, 2013 at 03:02.
mscheng is offline   Reply With Quote

Old   September 9, 2013, 08:10
Default
  #2
New Member
 
Maosong Cheng
Join Date: Aug 2012
Posts: 19
Rep Power: 3
mscheng is on a distinguished road
sorry! the inlet velocity is 0.5m/s.

Last edited by mscheng; September 10, 2013 at 03:04.
mscheng is offline   Reply With Quote

Old   September 10, 2013, 02:45
Default
  #3
Senior Member
 
Håkon Strandenes
Join Date: Dec 2011
Location: Norway
Posts: 110
Rep Power: 9
haakon will become famous soon enough
I really struggle to get a grip on what the problem really is. Perhaps you could try to reformulate your question/problem? It might as well be good to have some more details.

Perhaps you also could take a closer look on the forum rules? Especially #5 and #8: http://www.cfd-online.com/Forums/misc.php?do=showrules

One last tip: a general idea on how much time you should spend on formulating a question is that you should use as much time formulating your question as you expect people to use on writing answers.
Bernhard likes this.
haakon is offline   Reply With Quote

Old   September 10, 2013, 03:22
Default
  #4
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,173
Rep Power: 15
immortality is on a distinguished road
what are your BC's?
__________________
Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King.
To Be or Not To Be,Thats the Question!
The Only Stupid Question Is the One that Goes Unasked.
immortality is offline   Reply With Quote

Old   September 10, 2013, 03:49
Default
  #5
New Member
 
Maosong Cheng
Join Date: Aug 2012
Posts: 19
Rep Power: 3
mscheng is on a distinguished road
Quote:
Originally Posted by immortality View Post
what are your BC's?
U BC:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0.5 0);
boundaryField
{
side
{
type fixedValue;
value uniform (0 0 0);
}
outlet
{
type zeroGradient;
}
inlet
{
type fixedValue;
value uniform (0 0.5 0);
}
}

k BC:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 3.75E-003;
boundaryField
{
side
{
type kqRWallFunction;
value uniform 3.75E-003;
}
outlet
{
type zeroGradient;
}
inlet
{
type fixedValue;
value uniform 3.75E-003;
}
}
Epsilon BC:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -3 0 0 0 0];
internalField uniform 1.585453E-004;
boundaryField
{
side
{
type epsilonWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 1.585453E-004;
}
outlet
{
type zeroGradient;
}
inlet
{
type fixedValue;
value uniform 1.585453E-004;
}
}
nut BC:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -1 0 0 0 0];
internalField uniform 0;
boundaryField
{
side
{
type nutWallFunction;
Cmu 0.09;
kappa 0.41;
E 9.8;
value uniform 0;
}
outlet
{
type calculated;
value uniform 0;
}
inlet
{
type calculated;
value uniform 0;
}
}
p BC:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
side
{
type zeroGradient;
}
outlet
{
type fixedValue;
value uniform 0;
}
inlet
{
type zeroGradient;
}
}
================================================== ========
nu = 1.0631e-6

Thanks!
mscheng is offline   Reply With Quote

Old   September 10, 2013, 08:24
Default
  #6
Senior Member
 
immortality's Avatar
 
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,173
Rep Power: 15
immortality is on a distinguished road
blue region is wall?
how is grid?
__________________
Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King.
To Be or Not To Be,Thats the Question!
The Only Stupid Question Is the One that Goes Unasked.
immortality is offline   Reply With Quote

Old   September 10, 2013, 08:35
Default
  #7
New Member
 
Maosong Cheng
Join Date: Aug 2012
Posts: 19
Rep Power: 3
mscheng is on a distinguished road
Quote:
Originally Posted by immortality View Post
blue region is wall?
how is grid?
Hi immortality,
Yes, it is wall.
For the mesh, pls. refer to attached file!

Thanks!
Attached Images
File Type: jpg 1.jpg (68.8 KB, 7 views)
mscheng is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
OpenFOAM: LES turbulence model names Ollie OpenFOAM 5 January 7, 2013 10:24
Water subcooled boiling Attesz CFX 7 January 5, 2013 03:32
simpleFoam: Problem with k-omega Model near Wall okroud OpenFOAM Running, Solving & CFD 0 June 13, 2012 10:13
OpenFOAM: LES turbulence model names Ollie Main CFD Forum 1 April 11, 2011 13:03
Implementing a new LES Model in OpenFoam fs82 OpenFOAM 6 October 13, 2009 09:58


All times are GMT -4. The time now is 07:06.