# Buckingham Pi Theorm

1. Dec 28, 2009

### whiskydelta

Heya, I'm new here and really need help!

So I'm having trouble with the *Buckingham Pi Theorem*.

I think I've got the jist of it bar one thing...

So you have a bunch of variables e.g a force, velocity, denisty, length, viscosity, speed of sound:
f(F, V, roh, L, mu, a)

Do the (N variables - M fundamental dimentions):
6-3=3
to get the number of parameters:
pi1 pi2 pi3

BUT
How do know/determine which are the reoccuring variables:
eg.
pi1 = f(roh, V, L, F)
pi2 = f(foh, V, L, mu)
pi3 = f(roh, V, L, a)

AND
How do you know/determine which of the variables within each parameter doesn't go to the power of a letter (where the letters are exponents to be found)?

eg. pi1 = roh^c V^d L^e F

I hope this makes sense :)
Thanks

Last edited: Dec 28, 2009