How should I plot dv/dt in CFX?
Hi Guys,
Does anyone know How I can plot dv/dt in CFX where v is velocity and t is time?? I want to see the change of this term at specific time for my 2d simulation. I like to have a contour showing the changes of dv/dt. Thanks, Ali 
Time derivatives are partially supported in CEL.
Velocity time derivatives can be accessed with the ".Time Derivative" operator by setting up an additional variable as follows: ADDITIONAL VARIABLE: utderiv Option = Vector Algebraic Equation Vector xValue = u.Time Derivative Vector yValue = v.Time Derivative Vector zValue = w.Time Derivative END :) 
Thanks for your response.
What is utderiv? do I need to define a new variable named utderiv? I've started using CFX recentley. could you please explain more about the code? tnx :) 
utderiv is the name of the vector variable with du/dt, dv/dt, and dw/dt components.
This way could be simpler for you: 1) from CFXPre GUI define a new Additional Variable named "utderiv" (or whatever you like) 2) in the panel select: Variable Type = Unspecified; Units [m s^2]; Tensor Type = Vector 3) go to Domain>Fluid Models>Additional Variable Models and select "utderiv" in the selection area 4) flag the checkbox just below the selection area 5) type "u.Time Derivative" in Vector xValue, and so on. 
huh, I had no idea you could do that.
Reading a bit in cfx_ref.pdf I also found .Magnitude, .Gradient, .Curl, .Laplacian among others. Do they also work like .Time Derivative on AVs? 
Thank you so much Alemarins.
I have two more questions. In Vectorxvalue box I have to enter u.Time Derivative or Velocity u.Time Derivative??? My second question: It seems that I have to run my simulation again so as to get the results for my new variable right? since I've already run my simulation is there any way to find du/dt in CFDpost? Thank you for your help 
I got the answer for my first question. As you said u.Time Derivative works. I'm just curious to find a way so as to plot du/dt in CFDpost.

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