USER_GETVAR, Time Derivate operation on vector
 

Hello, I'm trying to extract the kinetic energy from my CFD domain during transient simulation using a USER FORTRAN routine. I want to create a new variable "time derivative of the velocity vector" with the function USER_GETVAR. ".Time Derivate" operator seems to work on scalar but not on vector. Is there anybody who encountered the same problem and found out a solution? Thanks

Re: USER_GETVAR, Time Derivate operation on vector
 

Dear Nicolas,

What kind of error you get when calling USER_GETVAR with

MyFluidPhase.Velocity.Time Derivative ?

Then, we can try to help you.

Opaque

Re: USER_GETVAR, Time Derivate operation on vector
 

Thanks for your help, I understood my mistake! I used the formula MyFluidPhase.Velocity.Time Derivate instead of MyFluidPhase.Velocity.Time Derivative. The confusion comes from the help file of CFX 11...

Searching for the Time Derivative file
 

Hello,

Has anyone found the Time Derivative expression?

I don´t find it and support help told me it doesn´t exist.

I really don´t know how to calculate the acceleration of fluid as the derivative of the Water.Velocity expression ?¿?¿

Any ideas?

Kind regards.

It does not exist. The previous posts in this thread are news to me - I don't think they work - but I would love to be shown to be wrong!