How Can We Calculate the Correlation Length L for Vortex Shedding?

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The discussion focuses on calculating the correlation length "L" for vortex shedding over a circular cylinder, which is crucial for determining the effective correlation factor "Kw" in wind-induced force analysis. The user seeks analytical or empirical methods to calculate "L," which is related to the maximum displacement "Ymax" caused by vortex shedding. Key variables are defined, including "b" (crosswind dimension), "St" (Strouhal number), "Sc" (Scruton number), and "K" (mode shape factor). The challenge lies in establishing a reliable method to derive "L" from these parameters. The conversation emphasizes the importance of understanding these variables to solve the problem effectively.
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Please Help!

In dealing with wind induced forces, caused by vortex shedding action over a circular cylinder, we must calculate the parameter "Kw" (effective correlation factor), which depends on "L/b", "L" beeing the "correlation lenght" (Eurocode).

Is there any method, analytical (or empirical), we could use, in order to calculate the parameter "L"?

I do thank you for any kind of help!

Best regards

Luís Fernando
guaiamum2010@gmail.com
 
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Could you define your variables?
 
Thank you, "RandomGuy88"!

According to Eurocode, the largest displacement "Ymáx/b", due to vortex shedding, can be calculated using expression:

Ymáx/b = 1/St^2 x 1/Sc x K x Kw x Clat

I can determinate all of them, except "Kw", which is a function of the so called "correlation lenght" ("L"), which, in turn, is a function of "Ymáx".

And that´s the problem! How can I calculate "L"?

Sorry, if I was too much problematic, and for my bad english!

Best Regards

Luís Fernando
guaiamum2010@gmail.com
 
I have no idea what any of your variables mean. What is b, what is Ymax, what is St, Sc, K...

Is L length over which turbulent velocity fluctuations are correlated? Or is something completely different?
 
Hi, RandomGuy88!

The meaning of those variables, is:

b - Crosswind dimension
Ymax - Maximum displacement due to vortex shedding
St - Strouhal number
Sc - Scruton number
K - Mode shape factor
L - Lenght over which vortex shedding occurs
Kw - Effective correlation length factor

(See Eurocode 1 - Action on Structures - Part 1-4 - General Actions - Wind Actions)

Best Regards

Luís
 

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