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

2D Boundary Layer Development in CFX11

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 28, 2008, 09:56
Default 2D Boundary Layer Development in CFX11
  #1
Chris Basciano
Guest
 
Posts: n/a
Hello Everyone,

I am running two very fundamental validation studies: (i) laminar boundary layer flow development and (ii) turbulent boundary layer flow development. Both simulations start with a uniform profile and simulate the development of a boundary layer along a no-slip wall at the bottom of the domain.

All simulations converge easily and produce expected results on a qualitative level. However, when comparing the velocity profiles of analytical approximations (Karman for laminar and Prandtl's 1/7 law for turbulent) the CFX solutions differ very significantly from the analytical solutions. I am convinced that this is due to an error on my part and am having trouble identifying the source of my error. Thus, I would greatly appreciate a critical review of my modeling approach and any tips that could be shared.

Here are more of the simulation settings: (a) Domain and Mesh - Domain is a rectangle with wall at bottom surface so a structured, hexahedral mesh is used with more elements near the wall than in the top region (high element density near wall) (b) Boundary conditions - right and upper boundaries are openings with zero ref. pressure (also tried top boundary being a free-slip wall) (c) Convergence Criteria - Max residuals below 1e-4 (d) Fluid - air w/ constant density, w/ ref. press of 1 atm (e) Turbulence model - SST / k-omega , low intensity at inlet and zero gradient at rightmost boundary

I would also like to know if any fellow CFX users have had similar experiences with this problem. Thank-you in advance for your time.

  Reply With Quote

Old   August 28, 2008, 17:15
Default Re: 2D Boundary Layer Development in CFX11
  #2
dummydummy
Guest
 
Posts: n/a
Have you checked the first cell height that you used in the mesh? This value is very important for capturing turbulent boundary layer. Make sure you using an appropriate Yplus value. Hope this help

Cheers

  Reply With Quote

Reply


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
[GAMBIT] problems in boundary layer yubaibai88 ANSYS Meshing & Geometry 8 April 19, 2010 22:07
[Gmsh] Import problem ARC OpenFOAM Meshing & Mesh Conversion 0 February 27, 2010 11:56
Adapt mesh without modifying boundary layer cells? Freeman FLUENT 0 February 22, 2009 15:11
3D Boundary Layer Mario FLUENT 0 February 17, 2009 04:40
Please help with flow around car modelling! Tudor Miron CFX 17 March 19, 2004 20:23


All times are GMT -4. The time now is 13:06.