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Old   March 4, 2010, 09:10
Default Boundary Layer thickness
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Hi,

I have a CFD model and i am trying to improve the density of the mesh inside the BL via additional prism layers. One thing i want to know is how thick (aproximately) the BL is so i can calculate how many layers i need.

Does anyone know a way of estimating the thickness of the BL?

Cheers
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Old   March 4, 2010, 10:31
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Most introductory heat transfer texts have chapters on how boundary layer models are developed starting with the Navier-Stokes equations. These eventually lead to algebraic expressions for b. l. thickness as a function of Reynolds Number or other appropriate dimensionless groupings of fluid properties, physical dimensions, and driving functions.

On my shelf of (antique) heat transfer texts are Schlichting (Boundary Layer Theory) and Chapman, (Heat Transfer). Others will be able to point to modern (and thus easier to find) texts.

Good luck!
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Old   March 5, 2010, 07:48
Default BL Thickness
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Hi,

If you're using commercial software try the user manual - CFX's details calculations for Y+ and B.L. thickness under "turbulence and near wall modelling".

Good luck.

Ianto
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Old   April 29, 2010, 00:06
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Hi,

The way on which I usually calculate the boundary layer is:

δ=5.2x/√Re

Last edited by Enrique Busquets; May 3, 2010 at 01:35.
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Old   April 30, 2010, 10:10
Default 3 dimensional wing with winglet design Using Catia
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hello, I am in problem in Design wing with winglet using catia. I have design 3 dimensional wing with taper, sweep ang twist. But i cant design winglet on the tip. I will analize the design with Fluent. Anyone could help me....
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Old   August 21, 2011, 06:28
Default empirical formula for B.L. thickness?
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Hi all,
I'd like to know boundary layer thickness around an airfoil (for ex. NACA 0012), I can use http://www.mh-aerotools.de/airfoils/javafoil.htm but the only result it can display are:
v/V: normalized surface velocity
d1: displacement thickness
d2: momentum loss thickness
d3: energy loss thickness
Cfl: ocal friction coefficient
H12: shape factor d1/d2
H32: shape factor d3/d2
flow state: laminar, turbulent, separated
y1: the first cell height required for y+=1 (multiplied by 100 resp. in %) value useful for grid generation


how can I calculate Boundary Layer thickness from any of these quantities?


or is there a semi-empirical formula to calculate it for an airfoil like the one posted above?

δ=5.2x/√Re
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Old   August 23, 2011, 15:27
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up; maybe I should have opened another topic
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