colebrooks equation
colebrooks equation
(OP)
Guys,
This is peanuts for you folks here. Won't take much of your valuable time.
Calculating pressure drops in pipeline, as I understand, needs first, an estimation of friction factor. I have referred to some books, and almost all of them gave me the following.
1/sqrt(f) = -2 x log10 [(e/ 3.7D)+ (2.51/Re sqrt(f))]
I learned that this was formulated in 1945. My question is, Is there any other type of colebrook equation, which is more recent or more accurate. Is the above one the current one?
(Is this really a stupid question, like asking if there is a better versin of ohms law or newtons third law of motion?)
thanks in advance
dinesh
This is peanuts for you folks here. Won't take much of your valuable time.
Calculating pressure drops in pipeline, as I understand, needs first, an estimation of friction factor. I have referred to some books, and almost all of them gave me the following.
1/sqrt(f) = -2 x log10 [(e/ 3.7D)+ (2.51/Re sqrt(f))]
I learned that this was formulated in 1945. My question is, Is there any other type of colebrook equation, which is more recent or more accurate. Is the above one the current one?
(Is this really a stupid question, like asking if there is a better versin of ohms law or newtons third law of motion?)
thanks in advance
dinesh





RE: colebrooks equation
1/sqrt(f) = -2 log10 [(e/ 3.7D)+ (2.51/(Re sqrt(f)))]
(the one you quote)
1/sqrt(f) = 1.74 -2 log10 [(2 e/D)+ (18.7/(Re sqrt(f)))]
1/sqrt(f)= 1.14+2log10(D/e)-2log10[1+(9.3/(Re e/D sqrt(f))]
www.cheresources.com give the three above and compares
RE: colebrooks equation
more accurate?
these are empirical equations based on specific piping and flow testing, usually in water.
RE: colebrooks equation
If you want an excel spreadsheet solver for colebrook equation go to,
http://me.queensu.ca/courses/mech441/spr/moody.xls
Also check this interesting page,
http://me.queensu.ca/courses/mech451/losses.htm
Regards,
I wish us all A Happy and Prosperous New Year
RE: colebrooks equation
http://www.cheresources.com/colebrook1.shtml
http://www.cheresources.com/colebrook2.shtml
http://www.cheresources.com/colebrook3.shtml
RE: colebrooks equation
You guys should be recognized for the direct, succinct, and valuable contribution to FreeFall's request. This series of articles goes to the grain of dealing with an out-dated, implicit equation and offers practical, up-dated explicit solutions that can be directly employed by engineers in their own programs or spreadsheets for quick and accurate fluid flow solutions. You guys have not only helped FreeFall, but you've assisted countless others who will read this thread. Kudos to you all.
Art Montemayor
Spring, TX
RE: colebrooks equation
RE: colebrooks equation
Thank you so much for ur clarifications. It really helped me.
Wishing you all a great 2005 ahead.
Dinesh
RE: colebrooks equation
Dr. Zaragola’s experiments with the Princeton University super pipe have redefined Prandlt’s smooth pipe law. The partially turbulent flow portion of the GERG equation conforms to the Zaragola equation.
For more info, see the papers below:
http:
Paper 0202 - Taking the Rough With The Smooth – A New Look At Transmission-Factor Formulae
http:
Paper 0112 - A Tutorial on Pipe Flow Equations
RE: colebrooks equation
Regards,