moody question

[traffic]

Maybe this is real simple to a water guy but I'm not sure where to start.

you've got a 6" pipe, .0005 friction factor and a reynolds of 6.5x10-5

what is the moody friction factor?

 

[Road Guy]

not 100% sure, but is it covered by one of those tables in the CERM appendix?

I dont have it with me, but the question sounds familiar

 

[traffic]

thanks, that did it !!

 

[Blu1913]

I think you meant to say the relative roughness is .0005 in your problem statement, because you are using Moody to solve FOR the friction factor...

Secondly, Reynolds number cannot be 6.5 x 10^-5 as you have stated. Reynolds numbers are very large....not very small.

 

[JasonT33]

No, I believe he is looking for relative roughness because he is given pipe size. Given the friction factor and Reynolds number, you can determine relative roughness... and from the relative roughness you can determine what pipe material is being used based on the diameter of the pipe in question

Blu is correct about the Reynolds number though...if you had a Reynolds number that low, you would have "perfect" laminar flow, for lack of a better description.. (i.e. friction factor would be "1")

 

[Blu1913]

Ah yes, Jason you are correct. Maybe if I would have slowed it down a bit I might have noticed that.

Thanks.