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mean velocity through area

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Old   February 6, 2014, 10:31
Default mean velocity through area
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Hey guys,

is there any possibility to calculate a mean velocity through an area (not a plane), see figure.

I have an solution, but this is very very uncomfortable. I export a data file with the velocity values in normal direction to that plane. I have to import this file in Matlab and over an script file i can filter the values outside my area. with the velocity values of the area i can calculate my mean velocity.

is there any possibility to draw a polyline on my plane normal to the flow direction that describes my area A in CFX?

thank you guys
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Old   February 6, 2014, 10:59
Kevin Hoopes
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I would try a user surface in CFD-Post. You could use your matlab script to generate a csv file in the right format that you could then use in CFD-Post. This would create a surface just like any other surface in CFD post that you could use all the functions on. It seems straight forward from the help, the only trouble would be getting the connectivity information, but matlab has some triangulation functions that can help you there.
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Old   February 6, 2014, 11:07
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did u test the usage of user surface for ur problem ? in CFD-Post guide chapter

is the area of interest always on the same position ?

### edit ###
sorry for the repetition ... i did not update the site and saw the post of khoopes after i posted reply ... and finally i found no way to delete the post
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Old   February 6, 2014, 17:56
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Can't you calculate the mass flow rate over any arbitrary surface? There is built in calculator in CFX-Post to get that. And if you know your density you can get velocity from that.
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Old   February 6, 2014, 18:10
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Just thinking off the top of my head, and I assume you have the area in your model and it is not aligned with the coord system or is of odd shape/alignment:

1) In CFX post you can create an expressions:

Normal X*Velocity u
Normal Y*Velocity v
Normal Z*Velocity w

2) Create a vector variable with components of each of the above expressions.

3) Calculate area average of the vector magnitude

If your area is aligned with the coord system, then there is no need to create the above, as I hope you know.
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