Error in "Handbook of Hydraulic Resistance," I.E. Idelchik

[peaktop]

The formula for tau in Diagram 8.3 of the 3rd and 4th editions should be (2.4-l.bar)*10^(-phi(l.bar)). The values in the table are ok.

Fudd's First Law of Opposition: "If you push something hard enough, it will fall over."

Teslacle's Deviant to Fudd's Law: "It comes in, it must go out."

 

[BigInch]

I only have the 2nd edition. Is that one OK?

"The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward X-CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[peaktop]

I don't have 2nd edition.

Can you compare the formula in the 2nd edition with the correct formula above?

Also, can you use the formula in the 2nd edition to check the values in the corresponding table.

Regards,

PT

 

[JohnGP]

I don't seem to be able to relate what you are asking with what I see in Diagram 8-3 of the 2nd Edition - Grid made of thickened laths or perforated thick plate. Maybe if you could post the page in question it would be easier to check, if you want to.

 

[peaktop]

See images at

http://www.flickr.com/photos/52974733@N08/

To avoid copyright issues, I'll remove these images once others have a chance to verify my claim.

Regards,

PT

 

[JohnGP]

Ok, the download wasn't so clear, but I could make out that the form of the equations has changed to that of the 2nd Edition, so that may have introduced some typos. If I had the time I could check the equations in the 2nd Ed, but that doesn't help you much.
Cheers,
John

 

[peaktop]

You wrote, "the form of the equations has changed to that of the 2nd Edition." Do you mean the form has changed *from* that of the 2nd Edition?

Can you provide the 2nd Edition form of the equations for tau and phi?

Thanks.

PT

 

[JohnGP]

Well, on the basis that I won't get shot for distributing 1 page out of a 640 page out-of-print edition.....

 

[peaktop]

Moving files from flickr.com to engineering.com:

http://files.engineering.com/getfil...c-a125-1fe27eea578c&file=Idelchik_Diag8-3.jpg

http://files.engineering.com/getfil...-4571-9b2c-a0f6f3e99f04&file=Idelchik_tau.jpg

 

[peaktop]

Tabulated values for tau agree exactly among 2nd, 3rd, and 4th editions.

2nd edition does not give a formula for tau, but a graph is given in Diagram 4-12. Does that graph look like the red curve in my file, Idelchik_tau.jpg?

PT

 

[JohnGP]

It does indeed look like your red curve. At the risk of doubling my fine, here is Diag 4-12 from the 2nd Ed.

 

[peaktop]

Thanks.

BTW, the graph in Diag 4-12 is taken from Idelchik's 1960 paper (Reference 30 on p. 537 of the 3rd edition).

PT

 

[napoleonm]

Here a copy of Diagram 8-3 from Ildechik 3th edition.

What is right: the table or the ecuation?.

The equation for tau does not works if you check with the table given.
As example let take l/dh = 1 so lbar = 1

Table stand: tau = 0.24

From equation
Tau = (2.4 - lbar) phi

Where phi= 0.25 + (0.535 (lbar)8)/(0.05+(lbar)7)
So:
With lbar=1 (one)…. phi= 0.7595

Them
Tau=(2.4 – 1)0.7595= 1.291182 (so different from table 1.291182 vs 0.24 )

If I use your corrected equation.

Tau = (2.4 - lbar) - phi
Tau = 0.7744 ( so different from table 0.7744 vs 0.24).

So what is right the table or the equation.?

Peaktop could you explain why you say the table is ok (step by step).

Here you can find a pdf with Diagram 8-3 from 3th edition, the pdf with the diagram you posted correspond to what edition?.

 

[napoleonm]

just to make it clear ( I did a copy paste from world):
so it did not take the exponent in the equations:

Tau = (2.4 - lbar)^phi .... eq 1
phi= 0.25 + (0.535 (lbar)^8)/(0.05+(lbar)^7) .... eq 2

solving for l/dh = 1 so lbar = 1:
phi= 0.25 + (0.535 (lbar)^8/(0.05+(lbar)^7)= 0.7595
Tau=(2.4 – 1)^0.7595= 1.291182

Tau from eq 1.291182 diferent from Tau from table 0.24

 

[vpl]

Maybe you should write/ e-mail the publisher and say there appears to be a discrepany in the document and could the author please check it out? I don't think that osting here will solve the problem.

Patricia Lougheed

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[napoleonm]

I would like to know how peaktop makes his calculations to get the values of the table..
peaktop please if you can send one of yours calcualtion I will check it, I am wondering how he or she do his cals.

Thanks.