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Find location @ Line where a variable has a certain value

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Old   March 29, 2010, 06:18
Default Find location @ Line where a variable has a certain value
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Hello!

I want to calculate the boundary layer thickness on a plate. For this I have created several Lines vertical on the plate an now I want to know the altitude atop the plate where the velocity reaches 99% of Uinf for the first time.

Is there any function that can tell me the coordinates of a certain variable on a Line?

Thanks in advance
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Old   March 29, 2010, 07:13
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Dmitry Volkind
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If Uinf is constant and Y is my plane normal and starts with zero at the wall, I would use CEL:
MyFunction1 = v - 0.99*Uinf
MyFunction2 = step (MyFunction1)
Then I would make a plot MyFunction2 = f(Y)
Axis segment where MyFunction2 = 0.5 is my boundary layer thickness +-tolerance
It's the first thing that comes to my narrow mind, still I think there must be a better way.
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Old   March 29, 2010, 08:20
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Hey Dvolkind,

Thanks for your reply! I have tried your solution but its still not working.
I get the Warning: "No Data exists for variable "my variable..."
I am working on that keep you updated.

cheers
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Old   March 29, 2010, 20:10
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Glenn Horrocks
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The problem with Dmitry's approach is it does not interpolate correctly between nodes. If you are going to do a lot of this I would export the nodal values along the line and do it either with a program or in excel/matlab/whatever. Then you will be able to batch a few of them together to do it more efficiently.
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Old   April 6, 2010, 03:51
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Hey Glenn,

Thats what I am about to do. Export all the data to matlab.
However I thought maybe there is a easy solution for this first step in Ansys.

Thanks

Camoesas
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Old   April 6, 2010, 12:02
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Can't you just create an isosurface of 0.99*Vinf and then export this surface? When calculating the isosurface Post will interpolate values fine.

(remeber to clip it to the are you're interested in)
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Old   May 6, 2010, 01:52
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It's probably too late, but I think extracting a polyline from a velocity contour plot is a good idea.
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