CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > STAR-CCM+

Is it realistic simulation? (Heat Transfer Simulation)

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

Like Tree3Likes
  • 1 Post By ryancoe
  • 1 Post By siara817
  • 1 Post By siara817

Reply
 
LinkBack Thread Tools Display Modes
Old   May 16, 2012, 06:38
Default Is it realistic simulation? (Heat Transfer Simulation)
  #1
Senior Member
 
Join Date: Dec 2011
Posts: 121
Rep Power: 5
fshak92 is on a distinguished road
We are trying to do a heat transfer simulations with the below settings.
We think that the temperature distribution is not so correct(particularly in the area which has been circled in the pictures in the attachment)
you can see the pictures of meshing of our simulation and the residual as well.

In summary, We have a machine which has been subtracted by a block(as a room).Now we have a machine inside the room with 6 surfaces.
The Machine has the constant temperature(26'C) and the 6 surfaces has a different constant temperature(21'C) and without any Velocity or mass inlet.

We used just one region(air) because we have the constant temperature of the machine and the block's wall.
The pictures are for our simulations with these conditions:
-Gravity
-Laminar
-Segregated Flow-Fluid Temperature
-Steady
-3-D
-Ideal Gas(we used also Constant Density with Boussinesq Model with thermal expansion coefficient(0.003) and nearly same result was achieved)

*The coupled solver also used but the residual was not convergent.

Meshing: BaseSize : 11mm
-Surface Remesher
-Polyhedral Mesher
-Prism Layer(3) (and also 12-no change)

Is there anybody know why the temperature distribution is not correct?
Thank you in advance.
Attached Images
File Type: jpg Meshing.jpg (89.3 KB, 64 views)
File Type: jpg Residual.JPG (73.8 KB, 49 views)
File Type: jpg TemperatureDistributionGeneralView.JPG (90.2 KB, 58 views)
File Type: jpg TemperatureDistributionProblematicArea.JPG (96.7 KB, 60 views)
fshak92 is offline   Reply With Quote

Old   May 18, 2012, 08:37
Default
  #2
Member
 
Ryan Coe
Join Date: Jun 2010
Location: Albuquerque, NM
Posts: 98
Rep Power: 7
ryancoe is on a distinguished road
Based on just looking at the images (not a great way to check to validity of a simulation) I would say the results seem believable.

The points of relatively low temperature that you point out may be areas where convection is causing a significant flow over the machine (You could check this by looking at velocity vectors or scalars).
fshak92 likes this.
__________________
Ryan
ryancoe is offline   Reply With Quote

Old   May 21, 2012, 07:02
Default
  #3
Senior Member
 
siara817's Avatar
 
siamak rahimi ardkapan
Join Date: Jul 2010
Location: Copenhagen, Denmark
Posts: 218
Rep Power: 9
siara817 is on a distinguished road
What is the turbulence intensity? Is it by default 0.01? It is a good try if you put TI=0.04.

Can you change the place of plane section and see the result?
make sure that you determined the temperature of all surfaces to be 26 degree.
Good luck
fshak92 likes this.
siara817 is offline   Reply With Quote

Old   May 21, 2012, 07:32
Default
  #4
Senior Member
 
Join Date: Dec 2011
Posts: 121
Rep Power: 5
fshak92 is on a distinguished road
Quote:
Originally Posted by ryancoe View Post
Based on just looking at the images (not a great way to check to validity of a simulation) I would say the results seem believable.

The points of relatively low temperature that you point out may be areas where convection is causing a significant flow over the machine (You could check this by looking at velocity vectors or scalars).
Quote:
Originally Posted by siara817 View Post
What is the turbulence intensity? Is it by default 0.01? It is a good try if you put TI=0.04.

Can you change the place of plane section and see the result?
make sure that you determined the temperature of all surfaces to be 26 degree.
Good luck
Thank you both for your reply

I checked the velocity streamline.but it seems there isnt any significant streamline in the mentioned areas.(the pictures is attached)

Also, I tried mostly the laminar model,,Do you know how can we find which model should be used for my simulation? laminar or turbulence?
I,ve read somewhere that if the area is not so big,then laminar case can be used,but im not sure.

Thank you both again in advance.
Attached Images
File Type: jpg VelocityGeneralView.jpg (101.5 KB, 32 views)
File Type: jpg VelocityStreamline.jpg (90.1 KB, 28 views)
fshak92 is offline   Reply With Quote

Old   May 22, 2012, 05:51
Default
  #5
Senior Member
 
siara817's Avatar
 
siamak rahimi ardkapan
Join Date: Jul 2010
Location: Copenhagen, Denmark
Posts: 218
Rep Power: 9
siara817 is on a distinguished road
Hello Omid,
I think because the velocity is less than 0.3 m/s, you can use laminar model.
I hope you could show us another section at the middle of your geometry.
fshak92 likes this.
siara817 is offline   Reply With Quote

Old   May 29, 2012, 07:00
Default
  #6
Senior Member
 
Join Date: Dec 2011
Posts: 121
Rep Power: 5
fshak92 is on a distinguished road
I tried to decrease again the mesh size of my shape.I increased the number of mesh from 9 million to 15 million cells,(with 12 prism layers on the machine) but again there are some problem particularly in the Heat Transfer Coefficient of the machine.
I attach some pictures of the new simulation.
Thank you in advance again.
Attached Images
File Type: jpg HTC.JPG (68.7 KB, 25 views)
File Type: jpg Mesh-GeneralView.jpg (87.3 KB, 24 views)
File Type: jpg Mesh-zoom.jpg (105.2 KB, 23 views)
File Type: jpg Residual.JPG (66.4 KB, 25 views)
File Type: jpg TemperatureDistribution.JPG (51.9 KB, 25 views)
fshak92 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
Quenching simulation : how to set up a conjugate heat transfer between solid&liquid Rockda FLUENT 23 March 15, 2015 00:19
Two-sided Wall Heat Transfer BC - No Separate Solid Mesh and No Heat Transfer Coeff swahono OpenFOAM Running, Solving & CFD 8 February 26, 2015 05:30
Heat Transfer in Porous Medium eryan STAR-CD 0 September 28, 2010 13:14
Heat transfer problem seojaho CFX 6 May 6, 2010 00:32
Natural convection - Inlet boundary condition max91 CFX 1 July 29, 2008 20:28


All times are GMT -4. The time now is 05:08.