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

Best way to compare two cases which should give the same results

Register Blogs Community New Posts Updated Threads Search

Like Tree2Likes
  • 1 Post By lovecraft22
  • 1 Post By sail

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 1, 2012, 12:30
Default Best way to compare two cases which should give the same results
  #1
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 460
Rep Power: 18
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Hi all;
I'm testing MRFSimpleFoam on a car with rotating wheels. I found 2 ways to achieve the rotation of the wheels so I would like to check that my results are the same in both the cases. From what I can see from the pressure and velocity fields in paraview they seem the same but I would like to be certain of that in a more "mathematical" way…

Can anybody please give me a suggestion on how to do that? For example it would be great to evaluate the difference in pressure between the two cases everywhere in my domain and then make sure that there numbers I'd get were close to 0 everywhere on my domain…

I would like to point out the the cases have the same geometry, mesh and boundary condition. I only used topoSet instead of setSet.

Thank you!
lovecraft22 is offline   Reply With Quote

Old   April 1, 2012, 12:54
Default
  #2
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 460
Rep Power: 18
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
I think I found a way in paraview:

I loaded both the geometries which were called, say, geomerty1 and geometry2. Then I applied a calculator filter to both of them and every calculator had these formulas:
p1=p for geometry 1
p2=p for geometry 2
this way I could easily identify what pressure was what.

At this point I selected bot the calculator-->filter-->append attributes.
I then used another calculator on the appended attributes with:
deltaP=p1-p2


If there a simpler way I would be glad to know of it.
arashgmn likes this.
lovecraft22 is offline   Reply With Quote

Old   April 1, 2012, 19:17
Default
  #3
Senior Member
 
sail's Avatar
 
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
Posts: 308
Rep Power: 17
sail is on a distinguished road
Hi Lore.

From what i've seen, on rotating wheels it is customary to plot the Cp vs angle on the circumference.

For the wake effect and/or turbulence quantities, plots of lines on the symmetry.

This should give you some graphs to look at. But your mehod seems reasonable too.
arashgmn likes this.
__________________
http://www.leadingedge.it/
Naval architecture and CFD consultancy
sail is offline   Reply With Quote

Old   April 1, 2012, 19:23
Default
  #4
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 460
Rep Power: 18
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
Thank you Vieri! I'll try that!
lovecraft22 is offline   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
How to give enough info to get help linnemann OpenFOAM 8 September 20, 2017 10:19
How to speed up the simulation of a large amount of similar steady state cases tss Main CFD Forum 4 November 5, 2010 15:36
wind tunnel results vs fluent pixie Main CFD Forum 1 August 20, 2009 09:02
Velocity spots in openFoam results Valle OpenFOAM Running, Solving & CFD 4 August 19, 2009 06:53
Standard CFD test cases? Damon Qualski Main CFD Forum 1 April 10, 2003 15:10


All times are GMT -4. The time now is 22:52.