CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Strouhal Numbers and Meshes

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

LinkBack Thread Tools Display Modes
Old   February 17, 2010, 06:15
Default Strouhal Numbers and Meshes
New Member
Join Date: Jun 2009
Posts: 10
Rep Power: 10
soggy316 is on a distinguished road
I am modeling flow past a circular cylinder in 2d

I have split the fluid domain into two parts - seperated by the box that I have drawn in this image -

Now, I am just validating the mesh for Re=100 before I get down to moving the cylinder.

Now for dynamic meshing i have to use a tri mesh around the cylinder. Now, when I run the case, I observe the following

1. I get a strouhal number exactly 1/2 of what I should be getting if my surrounding domain is tri (regardless of the presence of a quad boundary layer), refining the grid does not help.

2. If I use a quad grid I still get a strouhal frequency 1/2 that of the expected one.

the above two points used 1st order upwind scheme for momentum discretization

3. If i change the quad grid to QUICK discretization, then my strouhal frequency matches perfectly with the expected one.

4. The discretization has no effect on the tri mesh strouhal frequency

5. If in my most coarse tri mesh case, i reduce the time step by 1/10th then my strouhal frequency increases but is still some way off the expected value

Has anyone else experienced similar problems while using FLUENT? or am i missing something really simple?

My parameters are

inlet vel: 1m/s
density: 1 kg/m3
viscosity: 0.01 kg/ms2
Domain - 32mx16m
Subdomain - 2mx2m
soggy316 is offline   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
changing Mesh with known new points for shape kilerskill OpenFOAM 15 February 16, 2011 04:21
How to get the face numbers of a boundary? spwater OpenFOAM Running, Solving & CFD 1 March 24, 2009 02:01
Modeling in micron scale using icoFoam m9819348 OpenFOAM Running, Solving & CFD 7 October 27, 2007 00:36
IcoFoam parallel woes msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58
sliding meshes with periodic BC's Dan Brozozowski FLUENT 3 June 27, 2003 07:10

All times are GMT -4. The time now is 11:39.