CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Problem in cd of oscillating airfoil at high freq.

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

LinkBack Thread Tools Search this Thread Display Modes
Old   November 27, 2006, 02:31
Default Problem in cd of oscillating airfoil at high freq.
Posts: n/a

I managed to obtain results of cl/cd of an oscillating airfoil using fluent udf define_cg_motion. at frequency f=1, i managed to get a sinusodial graph for both cl and cd. They are quite close to the published results. dt=0.001

however, when i change f to 2 and rerun, i can get a sinusodial graph for cl (similar to published one) but the graph for cd is oscillating irregularly. i tried to reduce the time down to as small as dt=0.00025 but the result is still irregular.

i can't figure out what's wrong since i only changed the f from 1 to 2.

can someone help?

thanks alot!
  Reply With Quote

Old   August 22, 2017, 08:29
New Member
Join Date: Jun 2017
Posts: 12
Rep Power: 8
lfla is on a distinguished road
Ive done the same type of problem my results however differ greatly, i got a results file of flow time and lift coefficient and used alpha(t)=alpha(mean)+alpha(amp)sin(2*pi*f*t) in order to get results. Here's a copy of my results its quite clear that cl is decreasing with increasing alpha which shouldnt happen.
Thank you
Attached Images
File Type: jpg results.JPG (43.7 KB, 8 views)
lfla is offline   Reply With Quote


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
[Commercial meshers] Handling cyclic BC from gambit to openfoam for a cascade airfoil problem - OF 1.6 maverick OpenFOAM Meshing & Mesh Conversion 2 June 18, 2011 04:36
Fluid Structure Interaction problem for airfoil vinair39 OpenFOAM 0 February 8, 2011 07:57
Oscillating Airfoil - Dynamic meshing or user-defined velocity profile. DarrenC Main CFD Forum 5 July 19, 2010 22:33
problem in modeling flow over a 3d airfoil guess Main CFD Forum 8 March 20, 2010 13:54
High Turbulence Intensity Problem bwg FLUENT 1 January 13, 2010 13:09

All times are GMT -4. The time now is 21:42.