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

how to solve a problem involving both laminar and turbulent flow

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 2, 2011, 13:44
Default how to solve a problem involving both laminar and turbulent flow
  #1
New Member
 
Join Date: Jun 2011
Posts: 4
Rep Power: 15
seefd is on a distinguished road
hi..im trying to solve a double tube heat exchanger problem and validate it with the experimental value in which the flow inside inner tube (hot water) is turbulent and the flow in the outer tube (cold water) is laminar

so in the "viscous" tab in defining models, which option should i select; whether laminar or k epsilon??

i tried solving it considering it as turbulent as a whole and selected k epsilon, but on doing so the outlet cold temperature went beyond the value of outlet hot temperature by some decimals...why is it so????
but the value of the outlet hot temperature was comparable with the experimental...why is this happening??

also i tried solving it as fully laminar, but now the cold outlet temperature was exactly same to the experimental but the hot outlet temperature was much higher than the real hot outlet temperature. why this happens??
please help

also please tell how can i solve such a problem quite accurately....


please post and help..

thanking in advance.....
seefd is offline   Reply With Quote

Old   June 3, 2011, 04:20
Default
  #2
Senior Member
 
Amir's Avatar
 
Amir
Join Date: May 2009
Location: Montreal, QC
Posts: 735
Blog Entries: 1
Rep Power: 23
Amir is on a distinguished road
Hey,
you can set specific zone in FLUENT as laminar zone when the solver is set as k-epsilon for example.
define->BC->fluid zone->.... toggle on laminar zone
in such problems (heat transfer) it's better to use node based gradients.
Amir is offline   Reply With Quote

Reply

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
CFX Treatment of Laminar and Turbulent Flows Jade M CFX 18 September 15, 2022 08:08
Can I use turbulent model to solve a laminar flow? nikhil FLUENT 5 February 1, 2011 11:42
Laminar flow or Turbulent flow mech FLUENT 0 January 27, 2007 19:51
laminar and turbulent flow in one simulation msna FLUENT 0 January 27, 2007 18:35
modelling laminar and turbulent flow in the same Ol FLUENT 2 November 25, 2005 03:52


All times are GMT -4. The time now is 14:10.