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how to plot relative velocity on a plane in POST CFX

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Old   July 2, 2009, 21:18
Default how to plot relative velocity on a plane in POST CFX
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harry
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Hi,

In my case, a water filled cylindrical domain and its surrounding surface was setup as wall, which rotates at a certain speed, my question is how I can plot the velocity profile(radial, tangential, axial component) relative to the wall in the chart viewer. Can anyone help me with it please?thanks.

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Old   July 3, 2009, 06:32
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Hi,

I assume you did not use a rotating frame of reference - if you did you will have variables in both the stationary and rotating frame of reference in the output file by default.

If it is a stationary frame of reference simulation you will have to generate the rotating frame of reference by generating a vector field (in the variables tab) which is the velocity in the stationary frame of reference plus the component to convert it to the rotating frame. This should be simply r x omega (where "x" means the vector cross product)

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Old   July 4, 2009, 03:48
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HI, Glenn,

Thanks for your reply. Could you please tell me how to specify a rotating frame of reference in Pre-CFX? I tried to find it in tutorial, but it didn't help me a lot.Thanks in advance.
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Old   July 4, 2009, 07:20
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Hi Glenn,

Do you use domain motion in the basic setting tab of domain details in PRE CFX to specify rotating frame of reference(RFR)? I tried it, but I didn't find the variables of velocity in both stationary and rotating frame of reference in the variable tab in POST CFX.

Could you please help me with it? Thanks.
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Old   July 5, 2009, 06:39
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Hi,

Do the rotor/stator example in the tutorials. It uses a RFR.

Also note RFR is a license option which is not included in the basic CFX package. If you can't see it then you might not have that license option.

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Old   July 5, 2009, 11:21
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Hi Glenn,

Thanks, I got it. By the way, do you know how to express vector cross product in CFX? Thanks.

Harry
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Old   July 5, 2009, 19:26
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In what context? The CEL has a cross product function (I think) or you can write it out in full as a CEL expression. Is this what you mean?

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Old   July 6, 2009, 00:45
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Hi Glenn,

Yes, that's it. But I didn't find vector cross product function in CEL, maybe it doesn't support vector arithmetic. I gotta to write it out. I'm trying to generate the rotating frame of reference by generating a vector field using my current simulations with stationary frame of reference. And this requires to use cross product. Do I need fortran to write it, any good suggestions? thanks.
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Old   July 6, 2009, 01:24
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Hi,

CEL does not support vector variables, so make 3 CEL variables representing each component of the vector variable and then write out the cross product in terms of the components. A little messy but still pretty easy.

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