## Circulation around vortex core

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ridhwan
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### Circulation around vortex core

Hello, I'm new in Tecplot. Is there a tool in tecplot 360 to calculate circulation around the vortex core?

Or to calculate closed integration of $oint \vec{u} \cdot \vec{dl}$.

newby

Chris Idso
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### Re: Circulation around vortex core

Hello Ridwan,

Are you asking whether Tecplot can display a vortex core, or are you just asking if Tecplot can perform a calculation on a vortex core that has already been displayed?
Chris

Christopher Idso

Tech Support Lead
Tecplot, Inc

ridhwan
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### Re: Circulation around vortex core

Hello Chris,

I have already calculate and display a vortex core, vortex core radius as well. Now I'm going to calculate circulation around the core, but have no idea how can I do this in Tecplot.

Is there any tools in Tecplot to calculate circulation? OR
Can you give me some suggestion on how to extract data around the core (so I can do integration around it).

Many thanks.
Last edited by ridhwan on Wed Jan 27, 2010 4:57 am, edited 1 time in total.

davetaflin
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### Re: Circulation around vortex core

Hello, Ridhwan,

If you can define a closed path in your data over which to integrate, you can calculate circulation using the Analyze/Perform Integration menu option. In the Integrate dialog, for Type of Integration, select Vector Dotted with Unit Tangential, and select your velocity components for the Integrand. You then need to identify a line--a closed path--as your Domain of Integration. If you want to read more on specifying the domain of integration, click the Help button and scroll down a bit on the resulting help Web page. Click Integrate when you are done, and the circulation will be displayed as the integration result.

Dave

ridhwan
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### Re: Circulation around vortex core

Hello davetaflin

Many thanks for your suggestion, its work now.

Ridhwan

jim

### Re: Circulation around vortex core

I've uploaded Dave's macro <a href="http://www.tecplottalk.com/i/CreateCircl.mcr">here</a>. This creates a circular, I-ordered zone with an input radius, center and normal axis.

davetaflin
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### Re: Circulation around vortex core

Defining a closed path in three dimensions can be a challenge. If you have ordered data, you may be able to define an index range that encloses the desired location. The macro Jim mentioned gives you (with some editing) another option for creating a circular I-ordered zone in 3D. Once you have created the I-ordered zone for your integration, you can interpolate your volume data onto it using Tecplot's Data/Interpolate options.

ridhwan
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### Re: Circulation around vortex core

Thank you Jim for the macro.

I'll look forward to test the macro soon. At the moment, my circulation calculation works very fine using the Vector Dotted with Unit Tangential as suggested by Dave.

Many thanks for your help.

Yun
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### Re: Circulation around vortex core

hi, I am really new in Tecplot. Wish to get help.
I have to calculate the circulation around vortex core as well. I have velocity field and vorticity field. So i know where the vortex is.
But I don't know how to define the path(a circle around the core). In tecplot, there are only integrate over "cell volumes, I-lnes, J-lines, k-lines, I-planes, J-planes, k-planes".
My data is 2D.
Thank you very much if anyone can help!

rieuk
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### Re: Circulation around vortex core

Yes can anyone elaborate on how to create a new circular (closed path) zone onto which the data can be interpolated?

[EDIT] I suppose for circulation you can just calculate the vorticity and create a solid circular zone over which one integrates...but I don't know how to get the "line" zone i.e. hollow circular zone

ridhwan
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### Re: Circulation around vortex core

A closed circle can be created either by using macro given by Jim/Dave or what I did was creating a circular zone from Data/Create zone. The circular zone created however will have mesh with regular spacing. You need to interpolate data from simulation to this circular zone first and for the circulation, you need to take only the value at the outer most circle.

rieuk
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### Re: Circulation around vortex core

Ah ok so I should create the circular zone like I already have and the integrate around the boundary. I see, thanks.

houss
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### Re: Circulation around vortex core

Hi Tecplot users!
I've already used the Analyser function to extract vortex centre lines.now i want to display vortex core radius..is there any developed utility in tecplot for this purpose.
i would appreciate your help.

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