|
[Sponsors] |
![]() |
![]() |
#21 | |
New Member
Winson Chen
Join Date: Mar 2014
Posts: 5
Rep Power: 12 ![]() |
Quote:
Thank you for your quick and detailed reply. I will try your way and let you know the outcome later. Have a nice weekend. Winson |
||
![]() |
![]() |
![]() |
![]() |
#22 | |
New Member
Winson Chen
Join Date: Mar 2014
Posts: 5
Rep Power: 12 ![]() |
Quote:
Hi again Byron, I am using you method to generate some turbulence firstly in a channel. However, I have a couple of questions regarding the channel I need to generate: 1. Is the channel going to have top and bottom planes as walls and inlet and outlet as cyclic? In the boxTurb tutorial 6 planes are all cyclic. 2. In order to run the flow at the same Re in the channel (for my case it is Re_tau = 180), I have to mesh the channel very fine ( even finner than my original pipe to meet the CFL condition). Is it like this in your case too? 3. Do you by any chance know whether grading is allowed for the channel mesh? Thanks in advance! Winson |
||
![]() |
![]() |
![]() |
![]() |
#23 |
Senior Member
Join Date: Sep 2015
Location: Singapore
Posts: 102
Rep Power: 10 ![]() |
Dear Foamers,
I am trying to run a compressible turbulent pipe flow using rhoCentralFoam. I have already implemented two synthetic turbulence generator boundary conditions:
Both methods are producing 'turbulence' (see image) with the correct mean and covariance, but the turbulence decays quickly without developing into eddies as it should. I am at a loss as to why. Has anyone faced similar problems or have any idea as to how I can prevent the decay? Many thanks, USV P.S. I am not using a cyclic inlet/outlet arrangement since I would later need to apply these methods for more complicated geometries. |
|
![]() |
![]() |
![]() |
![]() |
#24 | |
Senior Member
Guilherme
Join Date: Apr 2017
Posts: 232
Rep Power: 10 ![]() |
Quote:
I would like to know of the others present in the topic if, the model used to describe the velocity in the fvSchenes (div U) can influence the laminarization of the fluid when related to the spacing of the mesh in streamwise direction? I'm having a problem with laminarization (LES - pipe), and my question is justified for this reason, because only the 'Gauss cubic' model manages to maintain the perturbations imposed by the perturbU. I do not know if it is related to the spacing in the streamwise direction. Thanks |
||
![]() |
![]() |
![]() |
![]() |
#25 |
Senior Member
Join Date: Sep 2015
Location: Singapore
Posts: 102
Rep Power: 10 ![]() |
Hello Guilherme,
I did manage to find the reason behind it. In my case, the shock capturing schemes TVD scheme in rhoCentralFoam were simply too dissipative to preserve the eddies. However, when I attempted to use rhoPimpleFoam (which does not use any shock capturing scheme), the eddies made it all the way to the end with little dissipation. Check out this post for further details: Link: Question about rhoCentralFoam and rhoPimpleFoam? |
|
![]() |
![]() |
![]() |
![]() |
#26 | |
Member
niewiemnic
Join Date: Jan 2018
Location: Niemcy
Posts: 80
Rep Power: 8 ![]() |
Quote:
Now I have the result of time 0,0025 s. So, with this result I did mapFields mapFields <source> -consistent and I changed the folder of the uniform gird to another folder "polyMesh" which has grading. But it doesnt work... What will be the reason? |
||
![]() |
![]() |
![]() |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
turbulent pipe flow result validation | preetam69 | FLUENT | 1 | February 22, 2018 21:53 |
sonicFoam - pressure driven pipe: flow continuity violation and waveTransmissive BC | Endel | OpenFOAM Running, Solving & CFD | 3 | September 11, 2014 16:29 |
Simulating turbulent flow in rectangle pipe with rhoPimpleFoam | zqlhzx | OpenFOAM Running, Solving & CFD | 1 | January 6, 2014 05:24 |
Turbulent flow through a pipe with variable inlet velocity | lobstar | OpenFOAM Running, Solving & CFD | 8 | March 28, 2012 11:15 |
Appropriate model for turbulent, steady state pipe elbow flow | milos | OpenFOAM Running, Solving & CFD | 4 | July 9, 2009 02:24 |