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

drag coeffecient of a single cylinder

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 27, 2004, 11:05
Default drag coeffecient of a single cylinder
  #1
Allan
Guest
 
Posts: n/a
all the text books and references seem to suggest that the drag coeffecient for a circular cylinder for reynolds number 10000, 100000 are about 1.2 approximtely. but when i am using flent i get values of about 0.1- 0.2 (max). i dont seem to understand whats going wrong. i have consulted some people in this area but they tell me that i am right and they cant figure why fluent is giving me such weird values. please help me out here as i am in deep trouble and have a deadline to submit. thanking you. allan
  Reply With Quote

Old   January 27, 2004, 12:02
Default Re: drag coeffecient of a single cylinder
  #2
ace
Guest
 
Posts: n/a
Allan you might find it helpful to look at the reference values you give in the panel since the coefficients depend on them as well.

Also try different turbulence models......

Hope it resolves your problem.

Cheers....
  Reply With Quote

Old   January 27, 2004, 23:46
Default Re: drag coeffecient of a single cylinder
  #3
Anton
Guest
 
Posts: n/a
Yes, check the reference values that are being used to calculate lift and drag coefficients. There are default values like L=1m, etc. You have to change these to the appropriate values for your system.
  Reply With Quote

Old   January 30, 2004, 02:16
Default Re: drag coeffecient of a single cylinder
  #4
Qureshi
Guest
 
Posts: n/a
I guess the problem is still there, One can change and play around with the parameters to get the results to ones liking. There has to be some standard methodology so that whenever one intend to carry out analysis on shapes and configurations with unknown results. Can anyone throw some light on it?
  Reply With Quote

Old   February 3, 2004, 11:46
Default Re: drag coeffecient of a single cylinder
  #5
Allan
Guest
 
Posts: n/a
I contacted the Fluent engineer, who told me to increase the depth in the reference values to 10.

This increased the CD to the desired value (around 1). However, when I increase the flow velocity from the original value, the CD jumped to over 9000 (it should be around 0.3).

You can easily get the CD to the value you want by altering the depth value, but this isn't right.

Does anyone know if there is a standard method to find the correct depth value?

  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
Drag Coefficient Verification around Cylinder MFerris CFX 44 May 11, 2015 18:27
Incorrect Drag and Drag Coefficient for flow over a cylinder ozzythewise Main CFD Forum 8 June 13, 2012 06:24
Drag on non-infinite cylinder between parallel walls deltaquattro Main CFD Forum 0 September 10, 2009 13:01
Solver and geometry choose for drag coefficient calculation around circular cylinder at large Re lin OpenFOAM Running, Solving & CFD 3 April 16, 2009 10:50
Inviscid Drag at subsonic, subcritical Mach # Axel Rohde Main CFD Forum 1 November 19, 2001 13:19


All times are GMT -4. The time now is 16:49.