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

Flat plate trouble

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

LinkBack Thread Tools Display Modes
Old   October 16, 2001, 16:10
Default Flat plate trouble
Chetan Kadakia
Posts: n/a
I am modelling a flat plate, but I am having difficulties acheiving a reasonable number for the Cd. Could someone advise what I could be doing wrong. My Cd should be in at the magnitude of 10^-3, but Fluent is showing a magnitude of about 10^4.

If anyone has worked the flat plate in Fluent, please let me know what you have done to make it work.

  Reply With Quote

Old   October 16, 2001, 17:23
Default Re: Flat plate trouble
John C. Chien
Posts: n/a
(1). First of all, put your flat plate leading edge in the middle of your computational domain. On the left side, you have empty free stream. (2). Stretch the mesh in both directions centered around the leading edge. In this way, you have very fine mesh at the leading edge. And the mesh size increases in both direction (left and right). (3). Stretch the mesh in the normal to the plate direction, higher density near the leading edge. This should gradually increase in spacing downstream of the flat plate. Basically, you are trying to capture the boundary layer development and the thickening of the boundary layer. (4). Try to use both the high Reynolds number model and the low Reynolds number model. And follow the model guidelines in terms of Y+ at the wall setting. (5). If you still have problems, try to use uniform mesh near the wall, and along the plate. (stretching in x-direction will change the solution in my systematic tests a couple of years ago, using tri-mesh) You should try quad-cell near the wall also. (6). Flat plate case is the most fundamental test case, because the turbulence models are all supposed to re-create the result. Unfortunately, there is no guarantee when using a commercial code. (I am not saying they are useless, I am saying that each case must be validated for accuracy)
  Reply With Quote

Old   October 19, 2001, 03:05
Default Re: Flat plate trouble
Posts: n/a
7 orders of magnitude is too much, to be accounted by modelling, meshing or other physical/numerical reasons.

You are probably haven't set the correct reference values in the "Report/Reference Values" panel (see User's Guide).

  Reply With Quote


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
Flow Over a Flat Plate recon9 CFX 1 January 20, 2011 22:09
Calculate Drag force for flat plate vsun FLUENT 0 October 3, 2010 07:56
drag of flat plate with cavity Far FLUENT 0 May 18, 2010 04:57
entrance of a flat plate mc Main CFD Forum 0 April 24, 2007 22:38
Seperated Flow and Turbulence modelling flat plate Simon Mizzi Main CFD Forum 1 December 16, 2003 02:26

All times are GMT -4. The time now is 17:41.