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

Problems with Cyclic & init. BCs for turbulent (k-eps) pipe flow

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 28, 2009, 09:05
Default Problems with Cyclic & init. BCs for turbulent (k-eps) pipe flow
  #1
Senior Member
 
Florian Krause
Join Date: Mar 2009
Location: Munich
Posts: 103
Rep Power: 9
florian_krause is on a distinguished road
Dear Foamers!

currently I am trying to set-up and solve a case of a pipe flow with cylindrical cross section. The length of the pipe is L=5D with D beeing the pipe diameter. I am using pisoFoam with the k-epsilon RAS model in OF-1.6.x.

Since I want to couple the inlet and the outlet with a cyclic boundary condition, I have set-up my U as following:
---
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 1.4);

boundaryField
{
newCyclicInOutlet
{
type cyclic;
}

pipe_wall
{
type fixedValue;
value uniform (0 0 0);
}
}
---

for k and eps I just use some reasonable values for a turbulent intensity of about 10%

My first grid point normal from the wall is located, such that should be in the region y+ > 20.

The final; goal is to obtain a fully developed turbulent flow of a Reynolds number of 7000 based on the pipe diamter and the centreline velocity.

The PROBLEM when I perform the calculation until convergence of U.z is that the tends to become zero. So it seems that it either diffuses heavily or there is something wrong with the combination of my cyclic boundary conditions and my field initialization.

Would appreciate any suggestions!!! (just let me know if you need more info!)

thanks a lot!
Florian
florian_krause is offline   Reply With Quote

Old   September 28, 2009, 13:01
Default
  #2
Senior Member
 
Florian Krause
Join Date: Mar 2009
Location: Munich
Posts: 103
Rep Power: 9
florian_krause is on a distinguished road
Ok "solved" it. I have choosen a too large endtime for the set pipe length and initial velocity, so the diffusion makes sense.

Got a nice velocity profile - compared to some exp. and DNS data - for the Re_centreline = 7000 flow, when I look at the flow at ealier times.

Will try to use now some forcing term to lower the diffusion.

have a nice evening!

Florian
florian_krause is offline   Reply With Quote

Old   October 1, 2009, 16:35
Default
  #3
New Member
 
Huang
Join Date: Sep 2009
Posts: 11
Rep Power: 8
hhuang84 is on a distinguished road
Hey,
Can you just put the input files here? I am trying to do such a similar job in simpleFoam. but it fail to get converged. Thanks.
hhuang84 is offline   Reply With Quote

Old   December 1, 2012, 05:11
Default
  #4
Member
 
sqing
Join Date: Sep 2012
Location: Dalian
Posts: 77
Rep Power: 5
Sunxing is on a distinguished road
Hi Florian,

I want to know how do you set the 0/p document. May I have a look at it please?

Regards,

Sunxing
Sunxing 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
RSM problems, axisymmetric pipe flow Timon CFX 3 November 6, 2008 05:48
Pressure Drop - Please Help - Simple Pipe Flow Joe A. FLUENT 2 April 23, 2007 07:50
Pipe flow with obstacle - HELP Min FLUENT 5 April 10, 2007 17:23
Can 'shock waves' occur in viscous fluid flows? diaw Main CFD Forum 104 February 16, 2006 06:44
flow in pipe with momentum and energy source Atit Koonsrisuk CFX 3 March 29, 2005 16:58


All times are GMT -4. The time now is 21:30.