
#1
Feb1114, 01:14 AM

P: 247

Hello,
I was wondering if when calculating the fanning friction factor, do english units need to be used? The equation for the head friction is h_f = 4f(L/D)V^2/2 where L is the length, D is the diameter of the pipe, and f is the fanning friction factor. This ends up having units of length squared/time squared, but I think it should be power/mass 



#2
Feb1114, 04:19 AM

HW Helper
Thanks
P: 5,554

I don't know about your dimensional analysis. The Fanning friction factor is nondimensional.
http://en.wikipedia.org/wiki/Fanning_friction_factor BTW, your formula for head loss due to friction is incorrect. It should be: h_f = 4f(L/D)V^2/(2g) 



#3
Feb1114, 10:19 AM

P: 247

Is the g included whether you use english units or not? I get confused when I need to divide by g or not these days since we keep going back and forth with english and SI units




#4
Feb1114, 12:24 PM

HW Helper
Thanks
P: 5,554

Fanning Friction Factor
Yes, the g is always there, even in SI or furlongs per fortnight units. Do a dimensional analysis and confirm.




#5
Feb1114, 11:11 PM

P: 247

You can see why I was confused, this is directly and repeatedly on the lecture slides



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