Friction factor in rectangular channels
 

Hi all,

I've come across several published literatures on science direct and engineering village along the topic of 'heat transfer in rib-turbulated internal cooling passages' where they refer to friction factor as: f=ΔpD/2ρLu^2.

From basic fluid mechanics, I would have thought that given: Δp=f(L/D)(ρu^2)/2, friction factor 'f' should be f=(2ΔpD)/(ρLu^2)?? i.e. the '2' should be a numerator rather than denominator.
Am I missing something here???

Thanks,

Never mind! Found the answer to this... turns out there are two types of friction factors - fanning and darcy.