USER_GETVAR, Time Derivate operation on vector

August 2, 2007, 07:19

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

August 2, 2007, 10:04

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

August 3, 2007, 06:49

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...

mar · June 18, 2010, 07:25

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.

ghorrocks · June 18, 2010, 07:37

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!

August 2, 2007, 07:19	USER_GETVAR, Time Derivate operation on vector	#1
Nicolas Guest Posts: n/a	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

August 2, 2007, 10:04	Re: USER_GETVAR, Time Derivate operation on vector	#2
opaque Guest Posts: n/a	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

August 3, 2007, 06:49	Re: USER_GETVAR, Time Derivate operation on vector	#3
Nicolas Guest Posts: n/a	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...

June 18, 2010, 07:25	Searching for the Time Derivative file	#4
mar New Member María del Mar RF Join Date: Jun 2010 Posts: 3 Rep Power: 16	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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Physical Reason for stability of Implicit Schemes?	radhakrishnan	Main CFD Forum	26	October 3, 2023 23:05
how to set periodic boundary conditions	Ganesh	FLUENT	15	November 18, 2020 07:09
How to write k and epsilon before the abnormal end	xiuying	OpenFOAM Running, Solving & CFD	8	August 27, 2013 16:33
Modifying gravity vector and MRFomega a run time	nico765	OpenFOAM Running, Solving & CFD	3	December 22, 2007 11:41
unsteady calcs in FLUENT	Sanjay Padhiar	Main CFD Forum	1	March 31, 1999 13:32

June 18, 2010, 07:37		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,850 Rep Power: 144	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!