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

Forced convection over a flat plate

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

Like Tree1Likes
  • 1 Post By fabian_roesler

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 19, 2012, 18:45
Default Forced convection over a flat plate
  #1
Member
 
Jubayer
Join Date: Oct 2009
Location: The University of Western Ontario, London, Ontario
Posts: 42
Blog Entries: 1
Rep Power: 16
cm_jubayer is on a distinguished road
I have quick question. If I want to simulate forced convection heat transfer over a horizontal flat plate which solver would be the best choice?

Jubayer
cm_jubayer is offline   Reply With Quote

Old   January 19, 2012, 22:18
Default
  #2
Senior Member
 
n/a
Join Date: Sep 2009
Posts: 199
Rep Power: 16
deji is on a distinguished road
Hello. I am simulating free and mixed convection turbulent boundary layer flow with a low Mach number solver that I came up with based on fireFoam. So the question for you is what regime of forced convection are you simulating, is it incompressible or compressible?

Cheers,
Deji
deji is offline   Reply With Quote

Old   January 20, 2012, 11:01
Default buoyantPimpleFoam
  #3
Senior Member
 
Fabian Roesler
Join Date: Mar 2009
Location: Germany
Posts: 213
Rep Power: 18
fabian_roesler is on a distinguished road
Hi

You should go for buoyantPimpleFoam or buoyantSimpleFoam depending on your problem, whether it is steady state or not. If you have incompressible flow you can go for the boussinesq solvers and if fluid density is constant in addition you can set the volume expansion coefficient to zero.

Regards

Fabian
aero.rajat likes this.
fabian_roesler is offline   Reply With Quote

Old   January 20, 2012, 12:32
Default
  #4
Member
 
Jubayer
Join Date: Oct 2009
Location: The University of Western Ontario, London, Ontario
Posts: 42
Blog Entries: 1
Rep Power: 16
cm_jubayer is on a distinguished road
Thanks deji and Fabian. I am dealing with incompressible flow and natural convection is negligible compared to forced convection. At first I thought buoyant solvers solve U equation based on gradient of density only, so I added temperature to simpleFoam solver. After running my case with the temperature added simpleFoam solver, I am getting huge continuity error. But, now I see buoyantSimpleFoam/buoyantSimpleFoam has pressure term as well in the U equation. I will follow Fabian's advice which is to set alpha=0 to treat the flow as incompressible. Thanks.
cm_jubayer is offline   Reply With Quote

Old   January 20, 2012, 12:43
Default
  #5
Member
 
Jubayer
Join Date: Oct 2009
Location: The University of Western Ontario, London, Ontario
Posts: 42
Blog Entries: 1
Rep Power: 16
cm_jubayer is on a distinguished road
I tried to mean buoyantBoussinesqSimpleFoam/buoyantBoussinesqPimpleFoam instead of buoyantSimpleFoam/buoyantPimpleFoam.
cm_jubayer is offline   Reply With Quote

Old   January 22, 2012, 05:03
Smile Use buoyantBossinesqSimpleFoam
  #6
Senior Member
 
Fabian Roesler
Join Date: Mar 2009
Location: Germany
Posts: 213
Rep Power: 18
fabian_roesler is on a distinguished road
Hi

You should better go for buoyantBossinesqSimpleFoam. This solver is for incompressible flow with Boussinesq approximation for natural convection. There you can set the volume expansion coefficient to zero (no natural convection anymore).

Fabian

---

Well, didn't read your last post. So you're on the right track.

Fabian

Last edited by fabian_roesler; January 22, 2012 at 05:05. Reason: Last post by cm_jubayer
fabian_roesler is offline   Reply With Quote

Old   February 4, 2012, 01:49
Default wrong temperature values at the nearest cell of the plate
  #7
Member
 
Jubayer
Join Date: Oct 2009
Location: The University of Western Ontario, London, Ontario
Posts: 42
Blog Entries: 1
Rep Power: 16
cm_jubayer is on a distinguished road
Really need your help guys. As I said earlier in this thread that I wanted to simulate forced convection over a flat plate and compare the Nusselt number values with the Nuseelt number correlation for the turbulent boundary layer over flat plate [Nu = 0.037*(Re^0.8)*Pr^(1/3)]. I need this to see how OpenFOAM performs in case of forced convection heat transfer and also to educate myself so that I can use the knowledge for my research with much complicated geometry.

I am using low-Re SST komega model with very low turbulence (~0.01%) at the inlet. I have a uniform velocity (20 m/s) at the inlet. My domain is just a long box with bottom of the box as the plate (uniform fixed temperature). Sides of the boxes are empty (2D). I am using buoyantBoussinesqSimpleFoam with beta=0 and g=0 (no natural convection). After running the simulation, I am getting very low heat flux and thus very low Nusselt number compared to the turbulent boundary layer correlation . I ran the same geometry with same boundary condition in FLUENT and got a good match. Then I dug deep and found that both FLUENT and OpenFOAM uses gradT to measure heat flux. And there I found that the value of gradT at the wall (with near cell) is really low in OpenFOAM compared to FLUENT which is giving me low heat flux values. Can anyone suggest why my temperature value at the near wall cell is so different in OpenFOAM than FLUENT? Thanks.


Jubayer
cm_jubayer is offline   Reply With Quote

Old   August 6, 2012, 09:54
Default
  #8
New Member
 
Join Date: Jul 2009
Posts: 11
Rep Power: 16
Lodda is on a distinguished road
Quote:
Originally Posted by cm_jubayer View Post
Really need your help guys. As I said earlier in this thread that I wanted to simulate forced convection over a flat plate and compare the Nusselt number values with the Nuseelt number correlation for the turbulent boundary layer over flat plate [Nu = 0.037*(Re^0.8)*Pr^(1/3)]. I need this to see how OpenFOAM performs in case of forced convection heat transfer and also to educate myself so that I can use the knowledge for my research with much complicated geometry.

I am using low-Re SST komega model with very low turbulence (~0.01%) at the inlet. I have a uniform velocity (20 m/s) at the inlet. My domain is just a long box with bottom of the box as the plate (uniform fixed temperature). Sides of the boxes are empty (2D). I am using buoyantBoussinesqSimpleFoam with beta=0 and g=0 (no natural convection). After running the simulation, I am getting very low heat flux and thus very low Nusselt number compared to the turbulent boundary layer correlation . I ran the same geometry with same boundary condition in FLUENT and got a good match. Then I dug deep and found that both FLUENT and OpenFOAM uses gradT to measure heat flux. And there I found that the value of gradT at the wall (with near cell) is really low in OpenFOAM compared to FLUENT which is giving me low heat flux values. Can anyone suggest why my temperature value at the near wall cell is so different in OpenFOAM than FLUENT? Thanks.


Jubayer
Hello Jubayer,

have you meanwhile found a solution for your problem? Im working on a similar case and my heatflux is also to low.

Best regards

Lodda
Lodda is offline   Reply With Quote

Old   December 18, 2013, 15:47
Default
  #9
Member
 
Jubayer
Join Date: Oct 2009
Location: The University of Western Ontario, London, Ontario
Posts: 42
Blog Entries: 1
Rep Power: 16
cm_jubayer is on a distinguished road
Hi Lodda,

you can try 'nutUSpaldingWallFunction' at the wall for nut, 'omegaWallFunction' for omega. These are continuous wall function that gives profile up to y+ =0.

Jubayer
cm_jubayer is offline   Reply With Quote

Reply

Tags
forced convection, heat transfer

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
Flow Over a Flat Plate recon9 CFX 1 January 20, 2011 22:09
Calculate Drag force for flat plate vsun FLUENT 0 October 3, 2010 08:56
Coupled vs Seg - Natural vs. Forced Convection Alex Siemens 5 December 12, 2007 05:58
Free convection flow over vertical flat plate Polly Main CFD Forum 1 February 11, 2003 14:25
Free convection flow over vertical flat plate Polly CFX 0 February 11, 2003 03:51


All times are GMT -4. The time now is 14:58.