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

3D melting problem with natural convection

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 11, 2013, 10:58
Default 3D melting problem with natural convection
  #1
New Member
 
manuel
Join Date: Mar 2013
Posts: 5
Rep Power: 13
flex00 is on a distinguished road
Hello fluent users,
my3D geometry consists of a steel pipe which is surrounded by a pcm (phase change material). The boundary condition of the inner pipe wall is convection with heat transfer coefficient and free steam temperature. The free steam temperature is above the pcm melting temperature. So the pcm should melt. There is also gravity. Thus I expect natural convection.
When the melting process starts on the interface between the steel pipe and the pcm, it happens in longitudinal oriented lines (see the picture). It does not melt uniform over the whole surface. After a few time steps the calculation dos not converge anymore.
My settings are:
All surfaces of the pcm are symmetrie. All properties of the pcm are a function of temperature (written in a UDF). I use Simple scheme, standard pressure discretization and the under relaxations factors are set by default. When i lower the relaxations factors, i have the same problem. Timesteps are 2 second. I also tried a much smaller time step (0,02s), but I did not work either.
What do I have to do to make the melting process going??
Thank you for your answers!!!
Attached Images
File Type: jpg pcm_melting.JPG (28.6 KB, 51 views)
File Type: jpg pcm_melting_residuals.JPG (35.2 KB, 46 views)
flex00 is offline   Reply With Quote

Old   March 12, 2013, 02:21
Unhappy
  #2
New Member
 
manuel
Join Date: Mar 2013
Posts: 5
Rep Power: 13
flex00 is on a distinguished road
Please can anybody help me!
flex00 is offline   Reply With Quote

Old   January 16, 2014, 11:50
Default
  #3
New Member
 
Yo
Join Date: Mar 2010
Posts: 2
Rep Power: 0
ymoucha is on a distinguished road
you are considering the flow equation in your model, the pcm has high viscosity compared to water, the dominant heat transfer mode is conduction and not convection, how did you model the density?
ymoucha is offline   Reply With Quote

Reply

Tags
convergence problem, pcm, solidification/melting

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
Natural Convection problem in Fluent - urgent NSV FLUENT 10 May 6, 2014 04:25
natural convection problem samantasubho FLUENT 0 October 6, 2010 10:07
Natural convection problem in CFX 11 Willy CFX 2 May 23, 2008 23:12
Adiabatic and Rotating wall (Convection problem) ParodDav CFX 5 April 29, 2007 19:13
natural convection problem Alanna Main CFD Forum 3 March 2, 2005 02:44


All times are GMT -4. The time now is 07:32.