Water Resources - Solve for Flow in a Pipe Network using Hardy Cross Method

[@lindseylarocque104]

For the K’ equation isn’t the D raised to the 5th and not 2

[@norajeanine]

It looks like this was adapted from CERM Example 17.10 with the same friction coefficients, lengths and diameters but different flow assumptions. If we use the assumed flows from CERM (which are in reasonable range for the flows in this problem), we'd get answer B. I'm confused as to why you didn't end up at the same answer as CERM, given that the only inputs that are different are the assumed flows. Thanks! Your videos have been super helpful. :)

[@Ivanov1979]

The entrance/exit flows are dieferrent than the one in the CERM example. :)

[@ryanv7075]

Thanks! Didn't pick up that you use both correction factors on the middle pipe from the book, now I know :)

[@Tl2004ever]

A little confusion on the assumption. You say we assume if it has a lower coefficient the flow will be higher. AB has a coefficient of 306, and AE has a coefficient of 367. So why did you assume the flow of AB to be 0.9 and assume AE 1.1?

[@DeagleBeagle]

Yeah that didn't make sense to me how he just randomly put numbers down.

[@joseaguilarmelgar3622]

@@DeagleBeagle We are only assuming the values of flow for each pipe at first. With the correction factor calculated, pipe ab is 1.04cfs and pipe ae is .96cfs. Remember the flow of ae is counterclockwise to the loop, so we subtract the correction factor. So at the end, pipe ab with lower k value has the greater flow.

[@mcruzatt]

I'm going to be taking the Computer Based PE and these equations are not on the updated CE Manual that is provided by NCEES. Does anyone have any insight?

[@CivilEngAcademy]

Not really... It's all very new. I would imagine they stick to the manual for the most part but I'm sure it will be updated often. If there are topics outside of what's in the manual then they'll most likely give you what you need in the problem itself.

[@mcruzatt]

@@CivilEngAcademy Thank you very much!

[@logman35]

@@CivilEngAcademy yeah, this is the trouble I'm having right now. I'm studying through some old practice tests while using the just the PERM and only looking at the CERM after the fact. I've gotten very few questions correct. All that to say, should I start studying these practice problems with the CERM to get a better understanding of the content and then studying updated practice tests with just the PERM in order to prepare for the actual exam?

[@shelleyrodriguez7959]

@@logman35 I am studying the PERM and doing practice exams I found amazon that apparently relate to the computer based exam.

[@logman35]

@@shelleyrodriguez7959 which practices tests have you found that relate to the CBT?

[@moonlantern]

Great Explanation, Much Appreciated... For K' equation D is raised to the power of 5 not 2; However, you used 5 in calculations.

[@samuelduchesne]

Can the Hardy-Cross method be adapted to solve for the diameters instead of the flow rates? eg.: change the diameters in each loops so that the sum of head losses is zero...

[@oleopathic]

Ncees pe hb 1.1, p. 313, 341. No ideal eqn ref page for this problem. Also, problem way too intense for even water PM section. Practice it but don't assume you'll have to suffer through all those iterations on real exam.

[@bukkavivek8011]

great exlaination....very helpful...

[@kaitlynhanley9120]

when you are calculating delta and expanding those summation terms, why do you subtract the terms associated with de and ae in the numerator, but ADD them when you expand out the denominator? if you're supposed to associate a negative sign with counterclockwise flow, why doesn't it carry over for calculation of both the numerator and denominator?

[@jordanchandler3704]

The denominator is Absolute value, marked by | |.

[@robertmertz4831]

Shouldn't the correction factor come out negative (-.14 cfs) given the equation you used? Then when added to the assumed flow rate end up as a subtraction for clockwise and an addition for counterclockwise flow?

[@mikemcf9189]

As written, the equation will yield +0.14 cfs because the 'ab'+'bd' is less than 'cd'+'ae'. The take-away is that if the assumed flow direction is aligned with the assumed positive (clockwise), then delta is added to the assumed flow rate. Otherwise, it is subtracted.

[@thomasgellermann1875]

D is to the 5th power in equation 17.131

[@argentinianbeast]

My only confusion is that shouldn't delta end in a negative value since there is a negative sign in the equation you wrote?

[@joseaguilarmelgar3622]

No

[@danamandia9783]

Hi want to ask if there is a condition when to stop iteration? My professor mentioned that you need to do it several times and substitute the value of Q every iteration you do till the difference of the flow you get and the previous flow is equal to 0?

[@CivilEngAcademy]

+Dana Mandia for the purposes of the PE exam I wouldn't do to many because you only have 6 minutes to solve the problem. In real life, yeah, but for the exam no.

[@Asahel717]

Very good explanation, thank you.

[@juver1102]

Am I missing something, calculated K of 306 is wrong, I got 11.3

[@CivilEngAcademy]

+Longwei Li The equation that I wrote for K'ab is wrong. It should the have diameter raised to the 5th not squared. I'll leave a comment. Thanks!

[@erzcav4793]

ive been wonderin bout it too.

[@aidapoori2881]

Thanks for sharing

[@samuelandraws7136]

Is this a typical morning question for civil transportation morning Part, I am talking about the new exam specs (2017) ?

[@CivilEngAcademy]

No, this is more of a water resources depth type problem. Someone requested it. Thanks!

[@oleopathic]

This is too intense for water PM. They might give you a simpler problem in PM.

[@hamzafilali4267]

Hello if for exemple the pipe ed in abde, are we going to add or subtract the correction ? thank ou

[@greenmountainboy2528]

Add

[@grapeshott]

anybody knows how to do linear theory iterations?

[@bonegrubber]

Good job!

[@mther123]

Best one

[@CivilEngAcademy]

Taher Mia Thank you!

[@nourelislamlounis3328]

wot about wood charles?

[@anniewang9728]

how start learn

[@faisalwaseem8118]

Kab calculates to ne 11.55 not 306? please explain