Flow Resistance of Connected Tubes

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Discussion Overview

The discussion revolves around the calculation of flow resistance in connected tubes of varying diameters and lengths, specifically focusing on how to determine the flow resistance of tube B, which has sections of different cross-sectional areas. The inquiry includes considerations of pressure required to maintain a specific flow rate through the tubes, assuming no turbulence is present.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asks how to calculate the flow resistance of tube B, suggesting the need to consider each section separately and whether to add the results.
  • Another participant questions the effect of tube lengths on pressure difference if viscosity is not a factor, and suggests considering Bernoulli's principle.
  • A clarification is made regarding the absence of turbulence in the system.
  • Repeated inquiries for responses indicate a lack of engagement or answers from other participants.

Areas of Agreement / Disagreement

There is no consensus on the method for calculating flow resistance or the implications of viscosity and turbulence, as participants express differing views and seek clarification.

Contextual Notes

The discussion does not resolve the assumptions regarding viscosity and turbulence, nor does it clarify the mathematical steps necessary for calculating flow resistance in the described scenario.

emh01
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i want to ask how flow resistance of connected tubes with different diameters is calculated.
as you see in the uploaded image we imagine that there are 3 tubes.
tube A is 2 meters long and cross section area is 2S.
tube B is also 2 meters long but first 1 meter has 2S surface area and last 1 meter has S surface area
tube C is 2 meters and has S surface area

now: how we calculate the flow resistance of tube B? do we calculate the first and last 1 meters each and add the results or different method? how we compare the resistances of 3 tubes

if connect a water pump to left of them and want to pass the same flow rate how much pressure we have to apply. what will be the compare of pressure magnitudes (3 tubes are already fully filled with liquid before pump)

add: we accept that there is no turbulance

thanks
 

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If there is no viscosity, how does the lengths of the various sections affect the pressure difference? Have you tried Betnoulli?
 
You are right, it has to be "There is no turbulance"
 
Chestermiller said:
If there is no viscosity, how does the lengths of the various sections affect the pressure difference? Have you tried Betnoulli?

You are right, it has to be "There is no turbulance" can you answer according to this
 
can anyone answer?
 

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