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

LES of channel flow: data, case files, technical report.

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

Like Tree14Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 13, 2019, 04:46
Default
  #21
New Member
 
Join Date: Jan 2014
Posts: 19
Rep Power: 9
camel is on a distinguished road
Nice! Thank you!
camel is offline   Reply With Quote

Old   May 31, 2020, 11:35
Default
  #22
Member
 
Arijit Saha
Join Date: Feb 2019
Location: Germany
Posts: 85
Rep Power: 4
ari003 is on a distinguished road
Respected Sir, it was so nice of you to share this topic here at CFD Forum. I am a newbie in OpenFoam and trying my best to learn most out of it but most of the time I suffer in finding the proper answer to my doubt in google.
Anyway I was doing some research with Channel 395 case with some modification like the boundary condition. In an unchanged channel flow the U and p folder look like the attachment shared along with this post. From my obserservation what I depicted is as follows:-
1.Bottom and top wall is having a no-slip boundary condition.
2. The solution has been provided with some initial condition i.e for 60000 cells they have provided some initial values.
3. The flow that is coming out of outlet is again fed to inlet and in this way the cycle goes on.
What I didnt understand is what is the significance of the side using it as a cyclic boundary condition?
Once I m clear with this part then I ll aim for my next target that is feeding some surface value to the inlet patch using mapped field and run the simulation. So in what way can I modify the bc in order to feed the inlet patch with some predefined value instead of the flow coming out from the outlet?
Attached Files
File Type: zip O.zip (1.2 KB, 1 views)
ari003 is offline   Reply With Quote

Old   June 1, 2020, 05:08
Default
  #23
Senior Member
 
Timofey Mukha
Join Date: Mar 2012
Location: Stockholm, Sweden
Posts: 116
Rep Power: 11
tiam is on a distinguished road
Quote:
Originally Posted by ari003 View Post
Respected Sir, it was so nice of you to share this topic here at CFD Forum. I am a newbie in OpenFoam and trying my best to learn most out of it but most of the time I suffer in finding the proper answer to my doubt in google.
Anyway I was doing some research with Channel 395 case with some modification like the boundary condition. In an unchanged channel flow the U and p folder look like the attachment shared along with this post. From my obserservation what I depicted is as follows:-
1.Bottom and top wall is having a no-slip boundary condition.
2. The solution has been provided with some initial condition i.e for 60000 cells they have provided some initial values.
3. The flow that is coming out of outlet is again fed to inlet and in this way the cycle goes on.
What I didnt understand is what is the significance of the side using it as a cyclic boundary condition?
Once I m clear with this part then I ll aim for my next target that is feeding some surface value to the inlet patch using mapped field and run the simulation. So in what way can I modify the bc in order to feed the inlet patch with some predefined value instead of the flow coming out from the outlet?

The idea is that the domain is infinite in the wall-parallel directions. We simulate that with cyclic boundaries. If you have walls on the side, that is going to lead to different results, since you'd have associated velocity gradients etc.



Regarding changing the boundary to some sort of inlet, it depends on what you intend to "feed". In any case, you put some sort of Dirichlet bc for U and zeroGradient for the pressure at the inlet, and the outlet set pressure to 0 and zeroGradient for velocity.
tiam is offline   Reply With Quote

Old   June 1, 2020, 05:23
Default
  #24
Member
 
Arijit Saha
Join Date: Feb 2019
Location: Germany
Posts: 85
Rep Power: 4
ari003 is on a distinguished road
Quote:
Originally Posted by tiam View Post
The idea is that the domain is infinite in the wall-parallel directions. We simulate that with cyclic boundaries. If you have walls on the side, that is going to lead to different results, since you'd have associated velocity gradients etc.



Regarding changing the boundary to some sort of inlet, it depends on what you intend to "feed". In any case, you put some sort of Dirichlet bc for U and zeroGradient for the pressure at the inlet, and the outlet set pressure to 0 and zeroGradient for velocity.
I also realized that once I remove the initial condition for all the cells from non-uniform to uniform the simulation is not running properly. But, for my use of timeVaryingMappedFixedValue at inlet I ve to make the initial condition as uniform otherwise how is it possible? Basically the cyclic bc runs when I put initial condition to all the cells but how can I run the same by feeding face-center value to the inlet patch?
Also attached with this post is the boundary field which I m trying to feed to the inlet, u can have a look.
Attached Files
File Type: zip boundaryData.zip (23.2 KB, 2 views)
ari003 is offline   Reply With Quote

Old   June 1, 2020, 06:12
Default
  #25
Senior Member
 
Timofey Mukha
Join Date: Mar 2012
Location: Stockholm, Sweden
Posts: 116
Rep Power: 11
tiam is on a distinguished road
Quote:
Originally Posted by ari003 View Post
I also realized that once I remove the initial condition for all the cells from non-uniform to uniform the simulation is not running properly. But, for my use of timeVaryingMappedFixedValue at inlet I ve to make the initial condition as uniform otherwise how is it possible? Basically the cyclic bc runs when I put initial condition to all the cells but how can I run the same by feeding face-center value to the inlet patch?
Also attached with this post is the boundary field which I m trying to feed to the inlet, u can have a look.

If you'll have an inlet and an outlet then initial conditions don't matter that much at all, they will be flushed out of the domain pretty fast anyway.
tiam is offline   Reply With Quote

Old   June 1, 2020, 08:56
Default
  #26
Member
 
Arijit Saha
Join Date: Feb 2019
Location: Germany
Posts: 85
Rep Power: 4
ari003 is on a distinguished road
Do you have any idea how can I make it working?
ari003 is offline   Reply With Quote

Old   June 4, 2020, 03:26
Default
  #27
Senior Member
 
Timofey Mukha
Join Date: Mar 2012
Location: Stockholm, Sweden
Posts: 116
Rep Power: 11
tiam is on a distinguished road
I'm sorry but I don't really understand what the problem is.
tiam is offline   Reply With Quote

Reply

Tags
channel flow, les, swak4foam

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


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 9 February 5, 2021 10:15
UDF issue MASOUD Fluent UDF and Scheme Programming 14 December 6, 2012 13:39
Problems in compiling paraview in Suse 10.3 platform chiven OpenFOAM Installation 3 December 1, 2009 07:21
PhD in turbulence Hans Main CFD Forum 14 October 8, 2001 03:03
fluid flow fundas ram Main CFD Forum 5 June 17, 2000 21:31


All times are GMT -4. The time now is 17:26.