
[Sponsors] 
July 15, 2010, 16:30 
"Velocity.curl" in CFXpost

#1 
Member
^_^
Join Date: Mar 2009
Posts: 36
Rep Power: 8 
I am using Ansys 12. in CFXpost, there are variables "Velocity.curl", "Velocity.curl X", "Velocity.curl Y", and "Velocity.curl Z".
I thought "Velocity.curl" is a vector. But when I used "ave(Velocity.curl)@blade", it gave me a scalar, and this scalar is not the square root of "Velocity.curl X", "Velocity.curl Y", and "Velocity.curl Z". What is "Velocity.curl" then? Thanks ! 

July 15, 2010, 19:04 

#2 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,045
Rep Power: 86 
It is the magnitude of the Velocity.curl vector, so is just a scalar.
Also the average of the magnitude of a vector field does not equal the sqrt(sum of squares of vector field components). Do the maths and you will find they are not equal. For instance, (sum(x))^2 does not equal sum(x^2) 

September 13, 2010, 19:44 

#3  
Member
^_^
Join Date: Mar 2009
Posts: 36
Rep Power: 8 
Sorry. What is the magnitude of a vector field?
Here is what I got: Velocity.Curl = 9102; Velocity.Curl X= 132.4; Velocity.Curl Y= 1289; Verlocity.Curl Z= 9.074; I still could not figure out how 9102 is related to other numbers... Quote:


September 14, 2010, 03:22 

#4 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 11,045
Rep Power: 86 
The magnitude is simply sqrt(X^2+Y^2+Z^2). This is basic vector maths, you won't get very far in CFD if you don't know things like that (sorry to be brutally honest).
Velocity.Curl is a vector field, made up of three scalar components Velocity.Curl X, Y and Z. At any point in the field the sqrt(X^2+Y^2+Z^2) will hold, but as I said previously this does not work if you average the variables over the field and expect sqrt(X^2+Y^2+Z^2) to hold on the averaged values. 

September 14, 2010, 12:10 

#5  
Member
^_^
Join Date: Mar 2009
Posts: 36
Rep Power: 8 
Thank you, ghorrocks.
I got what you mean. The values I got is the average value over the field instead of value for a signal point. Quote:


Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
CFX post legend modification  mactech001  CFX  3  December 25, 2011 23:12 
Variable for Number of Mesh Elements CFX Post  Matt  CFX  0  August 14, 2008 17:05 
Chart Generation in CFX Post  Vadim BainesJones  CFX  2  August 28, 2007 09:14 
boudary layer distance in CFX POST  toovac  CFX  2  February 15, 2007 09:34 
Tecplot for CFX post processing  pantangi goud  CFX  2  August 24, 2005 16:42 