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

Heated Walls

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 12, 2010, 09:56
Default Heated Walls
  #1
New Member
 
Vitor Braga
Join Date: Oct 2009
Posts: 28
Rep Power: 7
vitor is on a distinguished road
Hi,

I'm performing a simulation both in OpenFOAM, Fluent and Code-Saturne with the same conditions and the same mesh.
The case is very simple: an axial flow in a straight pipe with heated walls. The conditions are:

Inlet: 0,05 m/s; 313K ; pressure: zeroGradient
Wall: 500K or 2000K; pressure zeroGradient
Outlet: Zero gradient for all; except for pressure: fixedValue = 0.

I initialized turbulence using the equations in the User Guide (Lid-Driven cavity tutorial).

The issue is that, although Code-Saturne and Fluent give me the same results, I'm getting different results from OF. As you can see below:

Wall Temperature Outlet averaged Temp (Fluent) Outlet averaged Temp (OF)
[K] [K] [K]

500 315,7 319,4
2000 336,2 370,0

I'm using the bouyantBouusinesqSimpleFoam. Can anybody give me a hint about what might be happening?
If you really want to help, please try to run the simulation yourself (it's very quick) and check if you get the same solution.

Thank you.

BR,
Vitor.
vitor is offline   Reply With Quote

Old   August 13, 2010, 03:21
Default
  #2
Member
 
Join Date: May 2009
Posts: 31
Rep Power: 8
KrisT is on a distinguished road
What are the dimensions of the pipe? Is turbulence needed, the speed is so low, isn't the flow laminar?
KrisT is offline   Reply With Quote

Old   August 13, 2010, 08:11
Default
  #3
New Member
 
Vitor Braga
Join Date: Oct 2009
Posts: 28
Rep Power: 7
vitor is on a distinguished road
The diameter is 6m (about 20ft) and the lenght 20m (65.6ft), it gives a Reynolds number (for water) equal to 0,05*6/(1e-6) = 3e5 , wich is a lot greater than 2300, so the flow must be turbulent.

Thank you.
vitor is offline   Reply With Quote

Old   August 14, 2010, 04:12
Default
  #4
Member
 
Join Date: May 2009
Posts: 31
Rep Power: 8
KrisT is on a distinguished road
Big pipes.

One thing you could do would be to do the simulations on a smaller domain, where the flow is laminar. If you get the same results with the different solvers then you know it is related to the turbulence model.
KrisT is offline   Reply With Quote

Old   August 14, 2010, 13:05
Default
  #5
New Member
 
Vitor Braga
Join Date: Oct 2009
Posts: 28
Rep Power: 7
vitor is on a distinguished road
Good idea.

I think I`ll give it a try.

Thanks.
vitor is offline   Reply With Quote

Old   August 16, 2010, 14:47
Default
  #6
New Member
 
Vitor Braga
Join Date: Oct 2009
Posts: 28
Rep Power: 7
vitor is on a distinguished road
What puzzles me is that I've performed the same simulation with a heat flux at the wall instead of temperature at the wall, and it gave me the same results as Fluent and Code-Saturne.

But in the heat flux case I specified the cp (specific heat) of the water, and in the other case I only specified the Prandtl number.
vitor 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
Pipe with heated walls vitor OpenFOAM Running, Solving & CFD 3 July 15, 2010 16:20
wallHeatFlux for heated walls in laminar channel flow svens OpenFOAM Post-Processing 0 June 20, 2009 20:33
Radiation between heated rods lego Main CFD Forum 1 November 13, 2003 09:39
Radiation between heated rods lego CFX 0 November 12, 2003 09:44
thermal conditions of walls Stefan FLUENT 2 March 23, 2003 07:17


All times are GMT -4. The time now is 06:40.