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

Flow in closed box ?

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

Like Tree1Likes
  • 1 Post By boryan1965

Reply
 
LinkBack Thread Tools Display Modes
Old   October 16, 2013, 08:13
Default Flow in closed box ?
  #1
New Member
 
Borian
Join Date: Jan 2012
Location: USA
Posts: 8
Rep Power: 5
boryan1965 is on a distinguished road
Dear All,

I have tried to run a OF simulation on a flow through/around a pipe which is in the middle of closed box .The case is 3D, incompressible, steady . See the attached picture for details.

When my ''location-in-mesh'' point is inside the pipe , then sHM ignores the box and I get a solution/flow in the pipe only. When the ''location-in-mesh'' point is outside the pipe and inside the box respectively I have a flow/solution in the box ,but no flow in the pipe. See the attached picture - Box_No_Pipe, the pipe had not been meshed at all by SHM...

I would appreciate any ideas! Is it so hard to simulate a flow in closed circuit?

Thank you in advance!

Kind regards,

Boryan



================================================== ==================

“Success is one percent inspiration, ninety-nine percent perspiration.” -Thomas Edison
================================================== ==================

N.B. Damn right ...
Attached Images
File Type: jpg 3D Box.jpg (14.3 KB, 18 views)
File Type: jpg Box_No_Pipe.jpg (21.7 KB, 25 views)
boryan1965 is offline   Reply With Quote

Old   October 16, 2013, 08:27
Default
  #2
Member
 
Join Date: Nov 2012
Posts: 58
Rep Power: 4
startingWithCFD is on a distinguished road
If I understand your problem correctly, maybe it would help to give a bit of thickness to the cylinder, i.e. to define the tube wall as the volume between two concentric cylinders.
startingWithCFD is offline   Reply With Quote

Old   October 16, 2013, 09:12
Default Hi, thanks for the prompt reply
  #3
New Member
 
Borian
Join Date: Jan 2012
Location: USA
Posts: 8
Rep Power: 5
boryan1965 is on a distinguished road
I fact the pipe wall is 10 mm thick. The whole pipe was removed from the mesh when ''location -in-mesh'' point was in the box, but outside the pipe...

Obviously snappy Hex Mesh renders my pressure INLET/OUTLET as a external boundaries of the flow domain and ignores any geometry outside it, i.e. the pipe...

The general question is how one can possibly simulate such flow
boryan1965 is offline   Reply With Quote

Old   October 16, 2013, 14:40
Default
  #4
Member
 
Join Date: Nov 2012
Posts: 58
Rep Power: 4
startingWithCFD is on a distinguished road
Could you attach your case? It would be easier to understand the case this way.
startingWithCFD is offline   Reply With Quote

Old   October 17, 2013, 04:59
Default Thanks for the interest!
  #5
New Member
 
Borian
Join Date: Jan 2012
Location: USA
Posts: 8
Rep Power: 5
boryan1965 is on a distinguished road
The case is very simple, it is a part of bigger picture I would like to simulate. See the attached picture.

The pipe is in the middle of a closed box. Pressure INLET / OUTLET BC are applied on both ends of the pipe - 0 Pa & 500PA respectively.

sHM ignores the pipe from the model when ''location-in-mesh'' point is outside the pipe and inside the box.

Question is how one can simulate this in OF...Fluent runs closed circuit flows easily.

Attaching of constant & system OF folders would not be useful as I use a bespoke version of OF.

It seems to me that I need a ''multi-region'' solver...

Regards,

Boryan
Attached Images
File Type: jpg geometry.jpg (22.0 KB, 19 views)
boryan1965 is offline   Reply With Quote

Old   October 17, 2013, 11:38
Default
  #6
Member
 
Join Date: Nov 2012
Posts: 58
Rep Power: 4
startingWithCFD is on a distinguished road
I wanted to see exactly where "inlet" and "outlet" are in your system but you have verified my theory.
As far as I know, OpenFOAM does not allow internal patches, so, as you wrote, it recognizes them as external boundaries.
Also, multi-region solvers do not work with two adjacent fluid zones...

How exactly are you imposing the boundary values over there?
startingWithCFD is offline   Reply With Quote

Old   October 17, 2013, 11:46
Default How about a fan BC ?
  #7
New Member
 
Borian
Join Date: Jan 2012
Location: USA
Posts: 8
Rep Power: 5
boryan1965 is on a distinguished road
Right now I am thinking about removing the pressure INLET / OUTLET BC's and introducing a fan BC in the middle of the pipe...the fan will drive the flow and hopefully this will solve the issue with the domain boundaries...

Strangely enough there are not many examples of flow in closed circuit ....
boryan1965 is offline   Reply With Quote

Old   October 22, 2013, 10:48
Default Case solved !
  #8
New Member
 
Borian
Join Date: Jan 2012
Location: USA
Posts: 8
Rep Power: 5
boryan1965 is on a distinguished road
After some heavy pondering over the case is solved now - one has to remove boundary patches as INLET/OUTLET from the stl. geometry and the case folders and introduce an internal face Fan (baffleZone true; ) on the place of the fan...big thanks to all guys who have helped me !
Attached Images
File Type: jpg box_case.jpg (42.2 KB, 17 views)
startingWithCFD likes this.
boryan1965 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
Is it possible to use LES to simulate flow past trailing edge? jasonyuan Main CFD Forum 3 October 15, 2013 03:19
Gravitational water flow in closed channel. Szymon85 CFX 7 September 3, 2013 16:28
Closed loop pipe flow maddalena OpenFOAM Running, Solving & CFD 34 August 16, 2011 11:46
flow over a cylinder urgent! kevin FLUENT 7 June 8, 2006 01:19
Can 'shock waves' occur in viscous fluid flows? diaw Main CFD Forum 104 February 16, 2006 06:44


All times are GMT -4. The time now is 14:29.