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

Free convection BCs

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 22, 2008, 19:52
Default Free convection BCs
  #1
Craig Hildreth
Guest
 
Posts: n/a
Hello, let's say I would like to model an object that is heated that is exposed to the air around it. Heat transfer is in the form of free convection off the object. If one were to model the air volume surrounding this object what are some general guidelines? For example if the object were 1 x 1 x 1 m how big would the air volume around it typically be? Also, what type of BCs would one use on the extremities of the air volume? If anyone knows of some public tutorials similar to this I am all ears.

Currently I have casting that I modeling in CFX (I need CFX since air is present inside the casting). Right now I have heat transfer coefficient BCs on the casting fins or boundary. These were confirmed with some lab test data and calculated the standard way with Nusselt nos., etc., but I would like to actually see the airflow coming off the casting someday to see if all the fins are effective. Thus the desire to model the surrounding air.

Thanks,

Craig Hildreth
  Reply With Quote

Old   February 24, 2008, 17:45
Default Re: Free convection BCs
  #2
Glenn Horrocks
Guest
 
Posts: n/a
Hi,

The required size for the surrounding domain is problem dependant so you need to do a sensitivity check to establish the necessary size.

If you are looking for the details of flow in small cooling fins on the body then I would guess it could be fairly small (maybe extending 1m each side from the body based on a 1m body). You would need to check that - this is only a starting point.

Glenn Horrocks
  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
URGENT!!!! Combined free convection Mahyar FLUENT 0 August 13, 2008 00:39
CFX-5.5 simulating air free convection Dustin Lee CFX 0 April 16, 2003 02:54
BCs of Free convection flow Polly CFX 0 February 4, 2003 05:25
Free Convection in STAR-CD George Hampel CD-adapco 0 November 16, 2000 00:38
free convection heat transfer from a heated horizontal surface through a liquid to a thin cooled fin Kaushik FLUENT 1 May 8, 2000 06:47


All times are GMT -4. The time now is 07:02.