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Old   January 28, 2017, 23:50
Default Hairpin Detection
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Amar
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Hello everyone,

I'm trying to detect a hairpin vortex in the average field from DNS data set.
I tried to follow the procedure of Adrian (2007), sec II,
http://aip.scitation.org/doi/full/10.1063/1.2717527
but, unfortunately, I couldn't obtain same results.

The procedure is

1) Get the JPDF f(u,v) between u and v
2) Get the value of u and v (u0,v0) that maximize the ejection event in the second Quadrant Q2 such that -uvf(u,v) is maximum.
3) Conditionally average the velocity field around the point (u0,v0)
4) Calculate the swirling strength lambda_ci

Dose anyone have any suggestions?

Thanks a lot,

Amar
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Old   February 5, 2017, 17:50
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Jingchang.Shi
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If the input is averaged, can you expect to get vortex? I suspect it. I guess you should use raw velocity data.
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Old   February 5, 2017, 21:20
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Thanks Jingchang.Shi for reply.

But actually, I tried both of them. I used the raw velocity field and the averaged one, and both introduce same results.
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