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

Reference Values

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 13, 2012, 10:06
Default Reference Values
  #1
Member
 
nazareno mancinelli
Join Date: Mar 2009
Location: argentina
Posts: 35
Rep Power: 8
yochule is on a distinguished road
hi. i'm simulatig a 2D( 2ddp double precision solver) airfoil (naca0021). the chord lengh (was made up using gambit) is 0.14m. my problem is to correct set up the "Reference Values" to match the results with the published one (cd=0,019 cl=0,85)

A=0.14
cd=0,135-----cl=0,85
A=1
cd=0,019-----cl=0,1119

as you can see, if i set the reference area = 0.14, i have a correct solution for lift, but wrong with the drag.
whereas i set the reference area =1, i have a good drag, but a wrong lift

what its wrong here? whats i'm doing wrong? it is not possible to solve a problem with a chord lenght that is not = 1? i thought i would not be a big problem to change it to 14cm
can anyone help me? thanks in advance
yochule is offline   Reply With Quote

Old   May 13, 2012, 17:42
Default
  #2
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 675
Rep Power: 13
LuckyTran will become famous soon enough
Quote:
Originally Posted by yochule View Post
hi. i'm simulatig a 2D( 2ddp double precision solver) airfoil (naca0021). the chord lengh (was made up using gambit) is 0.14m. my problem is to correct set up the "Reference Values" to match the results with the published one (cd=0,019 cl=0,85)
you should use the same definition for each coeficient as the published result. what reference area did they use for drag and lift? the same or different references?

For airfoils, typically the reference area is the planform area which is sometimes equivalent to the chord length, keeping in mind this also changes with angle of attack.
LuckyTran is offline   Reply With Quote

Old   May 13, 2012, 17:49
Default
  #3
Member
 
nazareno mancinelli
Join Date: Mar 2009
Location: argentina
Posts: 35
Rep Power: 8
yochule is on a distinguished road
agree with that (the references its the chord lengh).
but the problem here is that (lets say) with the chord lengh as reference area in the reference value pannel, i do have a good result for cl, but the cd its wrong. can you get the point here?
yochule is offline   Reply With Quote

Old   May 13, 2012, 17:52
Default
  #4
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 675
Rep Power: 13
LuckyTran will become famous soon enough
Quote:
Originally Posted by yochule View Post
agree with that (the references its the chord lengh).
but the problem here is that (lets say) with the chord lengh as reference area in the reference value pannel, i do have a good result for cl, but the cd its wrong. can you get the point here?
if it's wrong then it's wrong, what can I do?
LuckyTran is offline   Reply With Quote

Reply

Tags
airfoil, drag coefficient, lift coefficient, reference values

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
It would be wonderful if a tool for FoamToTecplot is available luckyluke OpenFOAM Post-Processing 165 November 27, 2012 07:54
OpenFOAM 1.6-ext git installation on Ubuntu 11.10 x64 Attesz OpenFOAM Installation 45 January 13, 2012 13:38
Building OF 1.6 - CentOS 4.x Pytthon OpenFOAM 1 February 2, 2010 12:05
Simulation of a single bubble with a VOF-method Suzzn CFX 18 October 2, 2009 04:18
Fluent 2D Reference Values Adam FLUENT 1 January 16, 2009 03:58


All times are GMT -4. The time now is 16:58.