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

Different results from Solution and CFD-Post block

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 16, 2024, 10:45
Default Different results from Solution and CFD-Post block
  #1
New Member
 
jonas
Join Date: Feb 2024
Posts: 2
Rep Power: 0
Jonasbsh is on a distinguished road
Hello,

I was simulation a VAWT with a in stationary 2D-sliding mesh and wanted to get the Torque from the surface of the Rotorblad as result. The turning centre is the origin of the coordinate system. I let the torque be created in a result file during the Simulation. Everything went fine and there were no problems with the simulation at all. After checking the values for the Torque they seemed a bit high, so I calculated the cp value and it was ridiculous high with 0,699. After checking if I created the Torque data correct (yes) I went into the CFD-Post block to check it there. I went in the function calculator and selected the same location, rotorsurface, and the same centre and axis. It gave me smaller and more reasonable values which gave a realistic cp-value. But I'm not sure now, if I can trust those vaules. Btw, same with drag and lift, they are also different and smaller. Why are they different, when they are based on the same simulation? And which one are the right ones?

Maybe anyone knows what's going on?
I put both Torque values over time in the attachment.

Thank you!
Attached Images
File Type: png NACA-0018-moment-graph.png (26.3 KB, 3 views)
File Type: png MOMENT TOO HIGH.png (28.7 KB, 3 views)
Jonasbsh is offline   Reply With Quote

Old   March 16, 2024, 14:39
Default
  #2
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,678
Rep Power: 66
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
You are likely comparing apples to oranges. Drag and lift are based on a predefined direction vector. I'm guessing you have multiple blades where 1 vector does not a describe drag and lift in a meaningful way. In your mind lift is normal to the rotor surface but that's inconsistent with the lift-force and drag-force in Fluent.
LuckyTran is offline   Reply With Quote

Reply

Tags
ansys fluent, cfd - post, different results, torque

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Importing CFD solution data in CFD POST Aveek Pal ANSYS 2 February 24, 2020 03:04
plot intermittency factor of a fluent solution in CFD post alinik FLUENT 0 October 12, 2017 18:12
Ansys CFD POST constructs a solution history from wrong file. Wingman ANSYS 2 November 28, 2016 17:01
Future CFD Research Jas Main CFD Forum 10 March 30, 2013 12:26
IcoFoam parallel woes msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58


All times are GMT -4. The time now is 07:54.