CFD Online Logo CFD Online URL
Home > Forums > FLUENT

LES: boundary layer computation

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

LinkBack Thread Tools Display Modes
Old   July 12, 2005, 11:38
Default LES: boundary layer computation
Posts: n/a
Hi all,

I'm using LES in fluent with the Dynamic Samgorinsky model to compute the boundary layer flow of an incompressible fluid past a deep cavity of length L and deep D.

___<--L--> ____






The computational domain is as follow:


inlet.......................................pressu re outlet


The mesh is fine enough: y+ <1 on all the wall on the bottom of the computational domain.

On the upper part of the domain, symmetry boundary condition is used (at 3 D from the wall). At the outlet pressure outlet is used (at 4 D downstream the cavity). At the inlet (at 3 D upstream the cavity) the fully developped velocity profile comes from experiment.

The transverse (Oz) direction is homogeneous, so peridodic boundary are used in this direction with:

* a pressure gradient fixed to zero * flow direction fixed to x=0,y=0,z=1 * the periodic boundary condition are translational type

Convergence works fine but the velocity computed in the boundary layer upstream of the cavity don't match the fully devlopped profile of a turbulent boundary layer which is already injected at the inlet. And the skin friction coefficient decreases upstream from the cavity but in the experiment it's constant.

What's wrong with this configuration ? I have tried with 3D RANS modeling and it seems to work (for K-e for exemple) ...

Is the domain too short upstream from the cavity for an LES simulation ?

Is the Dynamic Smagorinsky model not appropriate ?

Are the periodic boundary conditions note appropriate for this configuration ?

Thank's for your help ! Francois

  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
Code from "Modelling and computation of boundary layer flows" DoHander Main CFD Forum 3 December 13, 2013 20:01
[GAMBIT] 3D boundary layer and meshing problem in GAMBIT 2.4.6 prashanthreddyh ANSYS Meshing & Geometry 1 December 20, 2011 01:35
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
errors Fahad Main CFD Forum 0 March 23, 2004 14:20

All times are GMT -4. The time now is 01:39.