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 robinfisichella March 4, 2010 09:10

Boundary Layer thickness

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

 otd March 4, 2010 10:31

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!

 Ianto March 5, 2010 07:48

BL Thickness

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

 Enrique Busquets April 29, 2010 00:06

Hi,

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

δ=5.2x/√Re

 le bien aime April 30, 2010 10:10

3 dimensional wing with winglet design Using Catia

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....:confused:

 Courant August 21, 2011 06:28

empirical formula for B.L. thickness?

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

 Courant August 23, 2011 15:27

up; maybe I should have opened another topic

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