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Astrid April 11, 2002 17:19

Global and local variables
Hi all,

In CFX 5.5 I have run a case with a cilinder from which the outer wall rotates with a certain constant speed. I have run it as a stationary case. The boundary condition on the outer wall is such that the specified u,v,w velocities provide the correct angular velocity.

Now in CFX-Post, when I view the global velocity on the outer rotating wall I obtain a global range between the correct minimum speed (= 0) and about 60-70% of the angular velocity. When I plot the local range I get the correct range between 0 and the angular velocity. (Btw, this does not only apply for the angular velocity, it applies for all variables)

Does anyone know what this difference means? Why is the local range broader than the global range?


Mike April 11, 2002 19:19

Re: Global and local variables
This sounds like it's because conservative values are used for the ranges instead of hybrid. Mike

cfd guy April 12, 2002 08:30

Re: Global and local variables
It sounds like a code bug for me.

cfd guy

Astrid April 14, 2002 16:51

Re: Global and local variables
Maybe. But which of them do I see? And where can I swith between both? Where is the button?

I want to be in controlllllll, Astrid

Mike April 14, 2002 19:02

Re: Global and local variables
Hybrid values aren't available for local ranges in 5.5. I believe 5.5.1 has the option to pick between the two.

Michael Bo April 15, 2002 06:28

Re: Global and local variables
Toggle between Hybrid (wall boundaries applied) and Conservative values (Raw calculated values) from within the Variable Editor in cfx post 5.5.

Michael Bo

Astrid April 15, 2002 16:46

Re: Global and local variables
So, it is a bug?

Mike April 16, 2002 00:50

Re: Global and local variables
I don't think this will make any difference to the values used for local ranges, but you can try it and see.

Mike April 16, 2002 00:52

Re: Global and local variables
i guess it depends how you define a bug. It's works as implemented, but maybe not how some people would expect it to work.

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