|
[Sponsors] |
question regarding LES of pipe flow - pimpleFoam |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
November 18, 2014, 04:17 |
|
#21 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
But does it work now, with a correct mesh?
Btw: You need to change p solver to GAMG as I wrote above...
__________________
The skeleton ran out of shampoo in the shower. |
|
November 19, 2014, 01:43 |
|
#22 |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
It still does not work, even with the correct mesh. Thanks for your suggestions nonetheless
Yes I do wall resolved LES. I am not sure about the boundary condition for k at the wall. Conceptually you are right that for a WR LES it needs to be 0. As for the nuSgs I suppose OF requires a nuSGS file in the 0 folder and I dont think the boundary conditions are used. I am going to try perturbing the flow with turbulence to see how that works out. Have you ever tried that option? btw, could you upload your pipe case for reference? |
|
November 19, 2014, 04:18 |
|
#23 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
Yes,
here it is. LES_pipe.tar.gz Can you upload your mesh somewhere? One thing: In your first pictures you show a turbulent profile (from one-eq. model), in your last pictures this looks like a laminar profile. Maybe the first was right, but you expect too much turbulence...
__________________
The skeleton ran out of shampoo in the shower. |
|
November 19, 2014, 04:25 |
|
#24 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
Yes, I think thats right.
__________________
The skeleton ran out of shampoo in the shower. |
|
November 20, 2014, 18:49 |
|
#25 | |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
Quote:
|
||
November 27, 2014, 04:31 |
|
#26 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
Daniel, I put the case on our server and let it run. I couldn't find any obvious mistake. You still need to wait a bit.
__________________
The skeleton ran out of shampoo in the shower. |
|
November 27, 2014, 16:10 |
|
#27 |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
Appreciate your help Philipp :-)
let me know if you happen to find anything. |
|
November 28, 2014, 07:12 |
|
#28 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
Daniel, after struggling that much without any outcome I try something different: I changed the boundary conditions from cyclic to mapped. I also made a thread about cyclic pipes for a different bur similar problem:
http://www.cfd-online.com/Forums/ope...-unstable.html So, maybe that will work. I can tell you after the weekend
__________________
The skeleton ran out of shampoo in the shower. |
|
December 2, 2014, 03:35 |
|
#29 |
Senior Member
Philipp
Join Date: Jun 2011
Location: Germany
Posts: 1,297
Rep Power: 27 |
Ok, It doesn't work either. I give up... maybe someone else can help.
__________________
The skeleton ran out of shampoo in the shower. |
|
December 3, 2014, 00:26 |
|
#30 |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
Hey,
I think because my reynolds number is less just by solving the equations without initializing turbulence wont help. But thanks for your help anyways. I am now trying to solve the problem by giving turbulence using boxTurb. Let me see how that goes. Will let you know if I manage to get some good results |
|
January 3, 2015, 14:26 |
|
#31 |
Member
|
Hi Daniel,
Have you solved your problem? I am trying to do LES for a pipe flow, but similar to the results that you shown in your first post of this thread, I don's see any turbulent structure after a very long time. Can you give some hints on the reason and solution for this problem? Best, Likun |
|
January 5, 2015, 10:15 |
|
#32 | |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
Quote:
I found the solution of this problem by using boxTurb utility in a square duct of the same length as the pipe to generate turbulence. Then mapping the turbulence from the duct to the pipe using the mapFields utility. This will be the initial condition which if you let run would give you turbulent structures in the flowfield. Let me know if you need any other clarification. |
||
January 6, 2015, 04:30 |
|
#33 | |
Member
|
Quote:
Hi Daniel, Thank you for your reply. I did what you suggested, and now my pipe is turbulent. However, I still have one doubt about the level of perturbation using boxTurb. I first generated a relatively small fluctuation with boxTurb, but then the turbulence was killed after some iterations. However, with a larger perturbation at the beginning (same order of the main velocity component), the turbulence survived. My question is that, does the extent of perturbation at the beginning influences the final results? Do you (or anybody) have any idea on what should be a proper level of perturbation? Thanks in advance! Best, Likun |
||
January 11, 2015, 02:12 |
|
#34 | |
Member
Daniel
Join Date: Jun 2014
Posts: 60
Rep Power: 12 |
Quote:
I am not entirely sure how the extent of perturbation affects the results because I havent really done a parametric study. Usually I have always taken the perturbation to be approximately 10% of the bulk velocity which is known. Hope that helps! |
||
January 12, 2015, 15:51 |
|
#35 |
Member
|
Dear Daniel,
Thank you for your reply. I think the initial perturbation should not influence the final results as long as the perturbation is enough to trigger turbulence. I simulated to pipe flow over a long time. The resolved kinetic energy seems does not change much over time. So, I think this should be converged. Best, Likun |
|
December 14, 2016, 05:34 |
streamwise or spanwise vortices
|
#36 |
New Member
Nitin
Join Date: Mar 2012
Location: Bombay
Posts: 16
Rep Power: 14 |
Dear Daniel
I am doing DNS channel flow in openfoam. I am unable to found streamwise or spanwise vortices even after 8000s. I would like to know how you solve your problem. |
|
December 24, 2017, 10:26 |
Hi
|
#37 | |
Senior Member
Guilherme
Join Date: Apr 2017
Posts: 245
Rep Power: 10 |
Quote:
|
||
December 26, 2017, 15:42 |
|
#38 |
Member
Arnout
Join Date: Nov 2010
Posts: 46
Rep Power: 16 |
||
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Issues on the simulation of high-speed compressible flow within turbomachinery | dowlee | OpenFOAM Running, Solving & CFD | 11 | August 6, 2021 07:40 |
setup problems - LES pipe flow with cyclic BC (1) and direct mapped inlet (2) | florian_krause | OpenFOAM | 22 | June 13, 2013 22:25 |
Pipe flow with pressure-inlet | lummz | FLUENT | 3 | October 13, 2012 14:29 |
Question regarding Fluent's Turbulent Pipe Flow Problem | clueless | Main CFD Forum | 0 | May 15, 2009 04:59 |
Question regarding Fluent's Turbulent Pipe Flow Problem | clueless | FLUENT | 0 | May 15, 2009 04:33 |