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Offline ndtma  
#1 Posted : 14 April 2022 13:52:18(UTC)
ndtma


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At present, my country Sri Lanka is undergoing its worst crisis since its independence in 1948, with severe shortage of essential items like fuel, cooking gas, electricity, medicine, milk and food items. As a result, we are compelled to be at home, while thousands are protesting in the capital city of Colombo and other major cities.

So, during this period I spent some time on SMath, and attempted the attached example in the internet solved by Hardy Cross Method using EXCEL

Essentially it is an overdetermined nonlinear pipe network with 22 variables {pipe flows) and 23 equations (16 Nodes + 7 Loops). The solution using SMath is based on a snippet using al_nleqsolve() posted by Viacheslav N. Mezentsev (uni) in SMath Forum.

Overdetermined_Nonlinear_Pipe_Network.pdf (433kb) downloaded 77 time(s).
Overdetermined_Nonlinear_Pipe_Network.sm (630kb) downloaded 80 time(s).

Edited by user 14 April 2022 13:55:31(UTC)  | Reason: Not specified

Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
thanks 4 users thanked ndtma for this useful post.
on 14/04/2022(UTC),  on 14/04/2022(UTC),  on 14/04/2022(UTC),  on 12/06/2022(UTC)

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Offline Ber7  
#2 Posted : 14 April 2022 15:40:58(UTC)
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Hello,ndtma
Fragments withal_nleqsolve() can be reduced to one line.
alnlegsolve(3).sm (636kb) downloaded 47 time(s).
alglib3.png

Edited by user 14 April 2022 15:44:56(UTC)  | Reason: Not specified

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Offline ndtma  
#3 Posted : 14 April 2022 16:03:58(UTC)
ndtma


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Originally Posted by: Ber7 Go to Quoted Post
Hello,ndtma
Fragments withal_nleqsolve()can be reduced to one line.


Hello Ber7,

Thank you very much for your very valuable suggestion.
It works fine.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline Razonar  
#4 Posted : 15 April 2022 02:33:11(UTC)
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Hi Nugegodage. I hope that the problems in your country can be solved, for the better, and that you and your family are well.

Thank you for this excellent example.

Your worksheet with a little different setup, using tables. No one new calc actually.

alnlegsolve v2.sm (905kb) downloaded 59 time(s).

Best regards.
Alvaro.
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on 15/04/2022(UTC)
Offline CBG  
#5 Posted : 15 April 2022 05:09:43(UTC)
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Hello Nugegodage

I hope that you and your family are very well in these times of crisis in your country.

I have made your example in the Epanet program, the results are shown in the graph below.

For the network to be valid, Node A must have an input pressure equal to or greater than 129.4 mH2O,
and Node C equal to or greater than 150.28 mH2O.

Internet_Network.png

Best Regards

Carlos
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on 15/04/2022(UTC)
Offline ndtma  
#6 Posted : 15 April 2022 06:33:25(UTC)
ndtma


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Hi Jean, Alvaro, Carlos and others.
Thanks for expressing your sentiments and encouragement.
We are safe and hope the situation will settle as early as possible.

Many thanks to Alvaro and Carlos for your suggestions on the example.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline overlord  
#7 Posted : 17 April 2022 14:43:24(UTC)
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Thanks for your sample.
I always like your irrigation examples.
Hope crisis in your country resolves too.

Regards
Offline ndtma  
#8 Posted : 17 April 2022 16:47:27(UTC)
ndtma


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Hi overlord.
Thank you for the sentiments and comments.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline ndtma  
#9 Posted : 26 May 2022 10:38:30(UTC)
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The subject revisited.
In my original post #1, the K values were simply computed using a given formula,
and head loss in each pipe computed accordingly.

In Method 1 of the attached example, friction factors (f) depend on the Reynold numbers (Re)
of each pipe and computed using a given formula involving Re.

In Method 2, NewtonRapson function of SMath is used for the numerical solution of the
implicit Colebrook-White equation to find f.

Many thanks to Ber7, Alvaro and Carlos for your earlier suggestions on the subject.

f_NR.jpg
Overdetermined_Pipe_Network_3 LOOPS-As per CHEGUIDE_al_nleqsolve.sm (287kb) downloaded 53 time(s).
Overdetermined_Pipe_Network_3 LOOPS-As per CHEGUIDE_al_nleqsolve.pdf (582kb) downloaded 32 time(s).

Edited by user 26 May 2022 11:11:11(UTC)  | Reason: Not specified

Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline CBG  
#10 Posted : 30 May 2022 05:06:37(UTC)
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Hello ndtmda

Here are the results of your example calculated
with a very old version of Pipe Flow Expert.

Overdetermined_pipe_network.png


Best Regards

Carlos
Offline ndtma  
#11 Posted : 30 May 2022 11:19:26(UTC)
ndtma


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Originally Posted by: CBG Go to Quoted Post
Hello ndtmda

Here are the results of your example calculated
with a very old version of Pipe Flow Expert.


Thank you Carlos!
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline ndtma  
#12 Posted : 06 June 2022 09:23:10(UTC)
ndtma


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Hello Carlos

Can you please explain how the marked values of gauge pressures are calculated?
Thank you.

bar.g.jpg
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline CBG  
#13 Posted : 07 June 2022 05:31:51(UTC)
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Hello Ndtma


Originally Posted by: ndtma Go to Quoted Post
Hello Carlos

Can you please explain how the marked values of gauge pressures are calculated?
Thank you.

bar.g.jpg



This pressure (0.9787 bar g) is caused by the water level in the tank, which is 10 meters.


The pressure of 0.6553 bar g is obtained by subtracting from the inlet pressure
of 0.9787 bar g. the losses in the pipe of 0.3234 bar g (3.304 m hd)

The system is not correctly resolved for the pressures, since nodes 3 and 8 have
pressures below atmospheric.

Best Regards

Carlos

Edited by user 07 June 2022 05:37:33(UTC)  | Reason: Not specified

thanks 1 user thanked CBG for this useful post.
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Offline ndtma  
#14 Posted : 07 June 2022 06:17:56(UTC)
ndtma


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Thank you Carlos.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline CBG  
#15 Posted : 07 June 2022 23:20:35(UTC)
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Hello Ndtma

Originally Posted by: ndtma Go to Quoted Post
Thank you Carlos.


You're welcome.



Changing the diameter of tubes 9 and 10 from 0.25 m diameter to 0.5 m, the problem of negative pressures is solved.

Another way to solve it is by increasing the level below the tank from 0m to 20m. and with the liquid level at 10 m

Overdetermined_pipe_network_Solution.png


Best Regards

Carlos
thanks 1 user thanked CBG for this useful post.
on 08/06/2022(UTC)
Offline ndtma  
#16 Posted : 08 June 2022 04:55:01(UTC)
ndtma


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Originally Posted by: CBG Go to Quoted Post

You're welcome.



Changing the diameter of tubes 9 and 10 from 0.25 m diameter to 0.5 m, the problem of negative pressures is solved.

Another way to solve it is by increasing the level below the tank from 0m to 20m. and with the liquid level at 10 m


Thank you Carlos. Your contributions are very much appreciated.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline ndtma  
#17 Posted : 11 June 2022 06:26:18(UTC)
ndtma


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Originally Posted by: CBG Go to Quoted Post
You're welcome.

Changing the diameter of tubes 9 and 10 from 0.25 m diameter to 0.5 m, the problem of negative pressures is solved.

Another way to solve it is by increasing the level below the tank from 0m to 20m. and with the liquid level at 10 m


Hello Carlos,

Can you please post the Pipe Data Table (with Pipe Number, Inner diameter, ..... Re, Friction Head loss)
for the case Changing the diameter of tubes 9 and 10 from 0.25 m diameter to 0.5 m..
as I get different results for this case.

Hope I am not troubling you.

Edited by user 11 June 2022 06:29:25(UTC)  | Reason: Not specified

Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
Offline CBG  
#18 Posted : 11 June 2022 22:19:34(UTC)
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Hello Ndtma

Originally Posted by: ndtma Go to Quoted Post


Hello Carlos,

Can you please post the Pipe Data Table (with Pipe Number, Inner diameter, ..... Re, Friction Head loss)
for the case Changing the diameter of tubes 9 and 10 from 0.25 m diameter to 0.5 m..
as I get different results for this case.

Hope I am not troubling you.



There is no problem.

Here is the requested table

Overdetermined_pipe_network_Solution_Change_Diam.png


Best Regards

Carlos
thanks 1 user thanked CBG for this useful post.
on 12/06/2022(UTC)
Offline ndtma  
#19 Posted : 12 June 2022 04:27:18(UTC)
ndtma


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Sri Lanka
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Thank you very much Carlos.
Look within!... The secret is inside you.
Best Regards
Eng. NDTM Amarasekera - Sri Lanka
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