CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

Apparent inviscid flow over rectangle problems

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 4, 2010, 14:58
Default Apparent inviscid flow over rectangle problems
  #1
Senior Member
 
jeff osborne
Join Date: Mar 2010
Posts: 108
Rep Power: 6
ozzythewise is on a distinguished road
Hi all,

I'm simulating flow over a rectangle at a Reynolds number of 10^5, using upwind discretization scheme, komega turbulent model, water at 20 degrees C as the fluid. I'm expecting to see recirculation just behind the leading edge of the rectangle but I can't see it. Attached is a picture of my stream lines. I'm using a grid set up such that I have a y+ of ~5. From my picture you can see that it looks like my simulation is completely inviscid, which makes no sense to me. Anyone have any ideas?

Thanks
-J
Attached Images
File Type: jpg velocityContour.jpg (57.5 KB, 14 views)
ozzythewise is offline   Reply With Quote

Old   October 5, 2010, 16:54
Default
  #2
Senior Member
 
jeff osborne
Join Date: Mar 2010
Posts: 108
Rep Power: 6
ozzythewise is on a distinguished road
Does anyone have an idea for this?

Thanks
-J
ozzythewise is offline   Reply With Quote

Old   October 6, 2010, 07:47
Default
  #3
Senior Member
 
jeff osborne
Join Date: Mar 2010
Posts: 108
Rep Power: 6
ozzythewise is on a distinguished road
If anyone has any ideas for this I would really appreciate it, I am really stuck on this one. I think the issue is with my wall functions, but I really don't know. Here is my 0/nut file:

dimensions [0 2 -1 0 0 0 0];

internalField uniform 0;

boundaryField
{
inlet
{
type fixedValue;
value uniform 0;
}
outlet
{
type zeroGradient;
}
topAndBottom
{
type symmetryPlane;
}
rectangle
{
type nutWallFunction;
value uniform 0;
}
frontAndBack
{
type empty;
}
}


Does anyone have any ideas to help me out?
Thanks
-Jeff
ozzythewise is offline   Reply With Quote

Old   October 6, 2010, 08:34
Default
  #4
Senior Member
 
maddalena's Avatar
 
maddalena
Join Date: Mar 2009
Posts: 436
Rep Power: 11
maddalena is on a distinguished road
Hi Jeff,
how do you define your rectangle patch in constant/polymesh/boundary? it should be wall.
And what about k and omega values? they should be kqRWallFunction and omegaWallFunction.
One more check: what OF version are you using?

hope it helps.
regards

mad
maddalena is offline   Reply With Quote

Old   October 6, 2010, 08:43
Default
  #5
Senior Member
 
jeff osborne
Join Date: Mar 2010
Posts: 108
Rep Power: 6
ozzythewise is on a distinguished road
Hi mad,

My rectangle patch is defined as a wall, and I am using the kqRWallFucntion and omegaWallFunction for k and omega respectively. I'm using OF v1.6. Any other thoughts?

-J
ozzythewise is offline   Reply With Quote

Old   October 6, 2010, 09:08
Default
  #6
Senior Member
 
jeff osborne
Join Date: Mar 2010
Posts: 108
Rep Power: 6
ozzythewise is on a distinguished road
Here's another noodle scratcher;

If I plot my wall shear stress at my last time step on the wall (close to the leading edge, x~10% down the wall) I get a value of about 1.8e-5. If however I plot my velocity gradients at the same location, I get a value of 12.5, which if I multiple it by the dynamic viscosity (in this case it's 0.001) I get a wall shear stress value (cause tau_wall = mu * wallGrad) I get a wall shear stress of 0.0125, which doesn't at all match up with 1.8e-5. Can anyone make anything of this?

-Jeff
ozzythewise is offline   Reply With Quote

Reply

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
What solver to use for inviscid flow simulation over missile mecbe2002 OpenFOAM 0 April 27, 2010 11:10
SIMPLE method for inviscid flow abcdef123 Main CFD Forum 0 February 26, 2010 08:24
Nozzle flow simulation in inviscid and viscous Cath FLUENT 0 January 28, 2007 02:16
Problems at transonic flow Mario FLUENT 0 September 26, 2005 05:27
High speed flow problems Sawa FLUENT 3 January 14, 2003 01:10


All times are GMT -4. The time now is 02:02.