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Old   May 12, 2010, 11:51
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Girish Gaikwad
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I want to define new variable {(velocity:Ycomponent)/(free_stream_velocity)}. But in system defined field functions I am not able to find function called velocity:Ycomponent. It is only showing velocity which is a vector quantity. How can I make all components of velocity visible in field functions tab? Please help me.

I searched on help menu and got this: System field functions are predefined field functions that are created by the models activated in the continua, and share a particular set of properties.

How can I activate velocity components and magnitude?
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Old   May 12, 2010, 14:15
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Pete Launie
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Velocity vector components are:
$$velocity[1]
$$velocity[2] <--velocity:Ycomponent
$$velocity[3]
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Old   May 12, 2010, 17:41
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Girish Gaikwad
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Thanks a lot.

But what is the syntax(definition) for free stream velocity that can be used in the above formula? And also it doesn't show the three components of velocity in field function tab (one of the example in help window showed velocity as well as its three components).
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Old   May 12, 2010, 20:24
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Pete Launie
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Quote:
Originally Posted by girishg View Post
Thanks a lot.

But what is the syntax(definition) for free stream velocity that can be used in the above formula? And also it doesn't show the three components of velocity in field function tab (one of the example in help window showed velocity as well as its three components).

Question: are you trying to get the velocity magnitude, or velocity at a freestream boundary?

for local velocity magnitude:

I don't know off the top of my head, but Velocity is a vector so...
sqrt($$velocity[1]^2+$$velocity[2]^2+$$velocity[3]^2) if nothing else.

I think there is a velocity magnitutde field function something like $velocity.magnitude, or mag($$velocity). I'm not sure I don't have access to the documentation at the moment.

For boundary velocity it's probably just easier to enter the velocity. i.e.

$$velocity[2]/12345
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Old   May 12, 2010, 21:32
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Vinicius Girardi
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for velocity magnitude, use mag($$Velocity) and for Y direction, use $$Velocity[1]. The directions X,Y,Z are represented by [0],[1],[2] respectively.
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Old   May 13, 2010, 09:21
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Girish Gaikwad
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Thanks a lot guys!!!
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