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

Yplus and CP diagrams acceptable?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   March 28, 2010, 12:41
Default Yplus and CP diagrams acceptable?
  #1
Member
 
smith
Join Date: Apr 2009
Posts: 75
Rep Power: 9
Zweeper is on a distinguished road
Hello everyone.

im doing a 3d simulation at the moment and because of problems i meshed my geometries without an boundary layer.

i provided a plot of yplus and a plot of the contours of pressure. as you can see, my yplus is roughly in the range of 50-500.

my question is now, these diagrams are full of data points, i guess thats because of the rough distribution of the mesh elements over the geometry surface?

But is this affecting the accuracy of my results? if so, how much? are they totally wrong now?
Attached Images
File Type: jpg Capture1.jpg (83.4 KB, 23 views)
File Type: jpg Capture2.JPG (95.8 KB, 18 views)
Zweeper is offline   Reply With Quote

Old   March 29, 2010, 05:13
Default
  #2
Member
 
smith
Join Date: Apr 2009
Posts: 75
Rep Power: 9
Zweeper is on a distinguished road
no suggestions?
Zweeper is offline   Reply With Quote

Old   March 30, 2010, 06:28
Default
  #3
Member
 
smith
Join Date: Apr 2009
Posts: 75
Rep Power: 9
Zweeper is on a distinguished road
last try
Zweeper is offline   Reply With Quote

Old   March 30, 2010, 11:52
Default
  #4
Senior Member
 
Chris
Join Date: Jul 2009
Location: Ohio, USA
Posts: 169
Rep Power: 9
Chris D is on a distinguished road
If you're plotting y+ along a wall, then, at a given x location, there is one data point for every node in the cross-stream direction. (Maybe z in your case?) That's why the points line up.

I would think that the accuracy of you simulation will depend more on resolving gradients in the streamwise direction (i.e., the boundary layer), not the cross-stream direction. You mentioned that you're not clustering the grid near the wall to resolve the boundary layer. You should be clustering the grid if you want to have a chance at a good solution.

As far as how bad your results might be, there isn't really a "one size fits all" answer, and nobody will be able to answer this for you without at least knowing what you're actually calculating.
Chris D is offline   Reply With Quote

Old   March 30, 2010, 12:00
Default
  #5
Member
 
smith
Join Date: Apr 2009
Posts: 75
Rep Power: 9
Zweeper is on a distinguished road
thanks a lot, that's the answer i expected!
Zweeper 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



All times are GMT -4. The time now is 04:14.