# How do you I calculate the Laminar Boundary Layer Y in meters

1. Jul 20, 2011

### firestarter7

1. The problem statement, all variables and given/known data

How do you I calculate the Laminar Boundary Layer Y in meters with Blasius Equation?
I have an expression for U (m/s) and u/U and u(m/s) and also eta=0.1, 0.2....5.2. I am wondering how one could calculate the y laminar boundary layer (m), the y buffer boundary layer (m), the ln y and the y turbulent boundary layer (m)... I know that I need different expression to calculate these...can someone tell me what expressions and how I get the y laminar/buffer/ln y/y turbulent?

This is an example of the sheet I have:
U (m/s) u/U u (m/s) Eta y lam (m) y buff (m) ln y y turb (m)
252.7 0 0 0 ? ? ? ?
252.7 0.047 11.8 0.1 ? ? ?
252.7 0.0939 23.728 0.2 ? ? ? ?
etc....

2. Relevant equations

I do think I can use the equation

Eta= y*sqrt(U/nu*x)
for ylaminar...but I have already found the tabulated data for Eta from Rosenhead's book in Laminar Boundary Layers...and I have the following X values:
X=...
25.91
27.27
28.94
30.08
32.64
34.62
36.19
39.13
41.99
43.44
44.57
45
44.57
43.44
41.99
39.13
36.19
34.62
32.64
30.88
28.94
27.27
25.91

The following Eta values
h
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
4.2
4.4
4.6
4.8
5
5.2

and U=252.7 m/s and u/U accordingly.

3. The attempt at a solution
For ylaminar do I only solve for y in the equation Eta= y*sqrt(U/nu*x)?
If so, how what are the expressions for ybuffer, ln y (meaning which y should I take the log function on, the laminar, buffer or turbulent) and yturbulent? Can anyone pls help me? I am unsure about how to see when the transition starts so I can go from ylaminar to ybuffer/ turbulent based on my y values...I am grateful if anyone can help me. Thanks