|
[Sponsors] |
Turbulent air flow through curved pipe - no vorticity |
![]() |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
![]() |
![]() |
#1 |
New Member
Join Date: Mar 2020
Posts: 18
Rep Power: 7 ![]() |
Hello everyone,
I am trying to simulate an air flow through a curved pipe (you can find the files here: https://www.dropbox.com/s/ahuf08jhwh...ulent.zip?dl=0). I already did a laminar simulation and it worked fine and returned the expected values. Now I want to do the same simulation with turbulence. It converges, but when I visualize the stream lines in Paraview, they are parallel and laminated just like in the laminar simulation (picture attached). I'd expect some vortices. I already increased the Reynolds-number by increasing the velocity at the inlet to 100 (nu=3*10e-5 and L=1)! Still no turbulence. I refined the mesh and ran the case with 3.5 million points. Still no turbulence. I decreased the convergence criteria to 1e-4. The simulation did not converge (with the fine mesh). Does anyone have an idea what else I could try? I'd appreciate any help. I am using simpleFoam and the turbulence model is RAS (kEpsilon). Thank you Maike |
|
![]() |
![]() |
![]() |
![]() |
#2 |
Senior Member
Ruiyan Chen
Join Date: Jul 2016
Location: Hangzhou, China
Posts: 162
Rep Power: 10 ![]() |
RAS models typically give you a smooth field, because it is the averaged field that it is calculating. To "see" vortices you need to do LES.
|
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Join Date: Mar 2020
Posts: 18
Rep Power: 7 ![]() |
Hello cryabroad,
thank you for your answer! I thought about that, too. I agree to that as far as the value of the velocity is averaged. But don't the streamlines represent the direction of the velocity which should not be affected by the averaging of the value of velocity? |
|
![]() |
![]() |
![]() |
![]() |
#4 |
Senior Member
Ruiyan Chen
Join Date: Jul 2016
Location: Hangzhou, China
Posts: 162
Rep Power: 10 ![]() |
The velocity used to construct the streamlines are also averaged, which is the time averaged velocity. I do think that in curved pipes you should get secondary flow though, but that depends on the curvature and flow rate and other parameters.
|
|
![]() |
![]() |
![]() |
Tags |
airflow simulation, kepsilon, simplefoam, turbulence, vortex |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
Verification of Turbulent Pipe Flow in OpenFOAM - kwSST | ajcav2 | OpenFOAM Running, Solving & CFD | 6 | April 28, 2017 15:51 |
Time averaged velocity in turbulent pipe flow | tsero | FLUENT | 1 | November 2, 2012 03:19 |
Appropriate model for turbulent, steady state pipe elbow flow | milos | OpenFOAM Running, Solving & CFD | 4 | July 9, 2009 02:24 |
air bubble is disappear increasing time using vof | xujjun | CFX | 9 | June 9, 2009 07:59 |
fluid flow fundas | ram | Main CFD Forum | 5 | June 17, 2000 21:31 |