Question on FluidPipe and FluidConveyor

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wooram-kim asked Nov 5, '24 Jeanette F commented Nov 20, '24

Question on FluidPipe and FluidConveyor

Hi,

I made and attached a model . (Fluid problem.fsm)

The model has 3 lines. Each line has a source that follows an exponential distribution and makes a box every seconds. The generated box is transformed into a liter of fluid and terminated at the end of line.

The only difference among the lines is the specification of fluid pipe as follows,

Line 1.

Maximum Content : 10.000

Maximum Flow Rate : 10.000

Line 2.

Maximum Content : 10.001

Maximum Flow Rate : 10.000

Line 3.

Maximum Content : 10.000

Maximum Flow Rate : 9.999

In case of Line 2 & 3, the Maxium Content is very slightly larger than Maximum Flow Rate.

I assume that the performance of the lines is almost identical because the input rate is very lower than the Maximum Flow Rates of pipes. But the run of 5,000 seconds shows very different results. It seems that the fluid conveyors of Line 2 & 3 cannot supply enough amount of fluid to the pipes.

Trying several tests, I've found the followings,

If the interval time is 1 (instead of exponential(0, 1, getstream(current))), the problem does not happen.

If the fluid conveyor is not used (ItemToFluid is directly connected to FluidPipe), the problem does not happen.

Software Version:

FlexSim 24.1.0

exponential distribution fluidconveyor fluidpipe

fluid-problem.fsm (48.5 KiB)

5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

Answer 1 · 2024-11-11T19:31:56Z

Jeanette F answered Nov 11, '24 Jeanette F commented Nov 20, '24

Hello @WooRam_KIM,

In the case where you are using a distribution in each source, they will not create items at the same time even if they have the same distribution. This means that the lines will have different content on them. By changing the arrival interval to 1 on the sources you are making the items arrive at the same time for each line so the content will be the same.

fluid-problem_1.fsm

fluid-problem-1.fsm (49.7 KiB)

· 2

5 |100000

Attachments: Up to 12 attachments (including images) can be used with a maximum of 23.8 MiB each and 47.7 MiB total.

wooram-kim commented · Nov 12 at 02:02 AM

The first figure shows the result of the model that you attached. The amounts of fluid that was terminated for 5,000 seconds are very similar.

I changed the process time of the Separator from 10 sec to 1 sec. The second figure shows the result of the modified model. In the first line, the fluid was terminated by 3668.05 liters for 5000 seconds. But in the second and third lines, the fluid was only terminated by less than 500 liters.

I think the second model is also supposed to show the result similar to the first model. I don’t know what made the significant difference.

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1731377098911.png (292.3 KiB)

1731377134822.png (313.4 KiB)

Jeanette F ♦♦ wooram-kim commented · Nov 20 at 05:54 AM

This has been submitted to the development team for further investigation.

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