Jump to content






Photo - - - - -

The Easy And True Solution Of Colebrook-White Equations




There are about 6 different equations. Mode 2.51 is… 1/sqrt(f)=-2*Log(Rr/3.7+2.51/(Re*sqrt(f))) Mode 1.74 is… 1/sqrt(f)=1.74-2*Log(2*Rr+18.7/(Re*sqrt(f))) Mode 1.14 is… 1/sqrt(f)=1.14+2*Log(1/Rr)-2*Log(1+(9.3/(Re*Rr*sqrt(f))) Mode 9.35 is… 1/sqrt(f)=1.14-2*Log(Rr+9.35/(Re*sqrt(f))) Mode 3.71 is… 1/sqrt(f)=-2*Log(Rr/3.71+2.51/(Re*sqrt(f))) Mode 3.72 is… 1/sqrt(f)=-2*Log(Rr/3.72+2.51/(Re*sqrt(f)))
Since the equation starts with "1/sqrt(f)=" and have a another thing of the right like "sqrt(f)". But the equations have not been solved since 1930. May folks have made "approximations", and some are close and some are not right. But I have learned a easy and true solution for different equations.
My solutions are easy and true in Excel.
For the Colebrook-White equations change to f=1/(______)^2 where the ______ is the made right equations.


Rr= 0.02722 (Rr number is at cell B1)
Re= 66,391 (Re number is at cell B2)
Equation 1/sqrt(f)=-2*Log(Rr/3.7+2.51/(Re*sqrt(f))) (Cells A6 to A25 is 1 to 20)
Solution =1/(-2*LOG($B$1/3.7+2.51/($B$2*SQRT(B4))))^2 (This will be at cell B6)
Guess f= 1 (Guess number at cell B5)
1 0.0550474813204902 FALSE (Enter at C6 is "=B5=B6)
2 0.0554204850782122 FALSE (Copy cell B6 and C6 down to places)
3 0.0554188475042326 FALSE
4 0.0554188546575135 FALSE
5 0.0554188546262658 FALSE
6 0.0554188546264023 FALSE
7 0.0554188546264016 FALSE
8 0.0554188546264016 TRUE
9 0.0554188546264016 TRUE
10 0.0554188546264016 TRUE
11 0.0554188546264016 TRUE
12 0.0554188546264016 TRUE
13 0.0554188546264016 TRUE
14 0.0554188546264016 TRUE
15 0.0554188546264016 TRUE
16 0.0554188546264016 TRUE
17 0.0554188546264016 TRUE
18 0.0554188546264016 TRUE
19 0.0554188546264016 TRUE
20 0.0554188546264016 TRUE


  • 0


Photo
Bobby Strain
Dec 28 2015 07:50 PM

Do you have a comparison of these 6 correlations? I have used the first for 30 years. It worked in the beginning, so I never changed. Should I?

 

Bobby

    • 0

I would recommend an amazing app-LEO Privacy, you can used your reserved number to track and find you lost phone. Good security app.

    • 0

Latest Visitors

  • Photo
    TOKSYLONE
    25 Jul 2018 - 01:33
  • Photo
    tarang.suthar
    15 Jun 2018 - 03:19
  • Photo
    cmouloud1999
    29 Mar 2018 - 01:29
  • Photo
    fc21
    25 Mar 2018 - 08:04
  • Photo
    ashishbp
    02 Mar 2018 - 20:31