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Old   August 8, 2013, 06:37
Arrow computing boundary layer thickness
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Liam
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Hi people,

Anyone knows how can I compute boundary layer thickness for an arbitrary geometry? I have seen some theoretical formulas for flat plates, but I am not sure if there exists a formula for any kind of problem...

Thank you so much
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Old   August 12, 2013, 06:29
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Fateme Sh
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first you need to find the first row height
regarding to your flow condition you can find your first row height with the help of yplus calculations in here:
http://geolab.larc.nasa.gov/APPS/YPlus/

then i think 12 rows is enough (base on my experiments and studies) for the boundary layer mesh
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Old   August 12, 2013, 06:47
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Hi aeroAngel,

I am seeing that those calculations are for a flat plate. Are the values computed here valid for an arbitrary geometry?

Thanks for your reply!
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Old   August 12, 2013, 07:24
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the nasa calculator is based on yplus calculations which is for any wall-bounded flow,
I've used it in my calculations for any shape ,like other engineers that i know
and I haven't seen something about not using it in my studies.

I asked other engineers and they agreed
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Old   August 12, 2013, 09:22
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Thank you so much! I will have to make several aproximations because freestream velocity is not given, I only know pressure values at inlet/outlet and I guess this info is not enough for the calculator...
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Old   August 12, 2013, 09:32
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Quote:
Originally Posted by Tensian View Post
Thank you so much! I will have to make several aproximations because freestream velocity is not given, I only know pressure values at inlet/outlet and I guess this info is not enough for the calculator...
Although it is true the inlet/outlet pressure is not enough, you can certainly have an initial guess for your reference velocity (which depends on your case)

After solving your case with the mesh corresponding to your assumption, you could use the solution to improve your reference velocity, in order to adapt your mesh to the physics of your case.
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