Why is water unable to flow from A and B to C in a branching pipe system?

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Homework Help Overview

The discussion revolves around a branching pipe system and the flow of water between points A, B, and C. Participants are examining the implications of pressure conditions at point B and how they affect flow rates and relationships between the variables involved.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning the meaning of variables such as h2 and whether they might be typos. There are discussions about the flow rates (Q1, Q2, Q3) and the conditions under which water can flow into or out of reservoir B.

Discussion Status

The discussion is ongoing, with participants seeking clarification on variable definitions and the relationships between flow rates. Some have offered insights into the implications of pressure differences in the system, while others are exploring the potential for misinterpretations of the original statements.

Contextual Notes

There are references to specific conditions under which water flow is analyzed, including pressure levels at reservoir B and the potential for drag in the pipes affecting flow dynamics. Participants are also considering the implications of closing off junctions in the system.

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Homework Statement


what does the author mean by if P is below the surface of B then h2 and Q2 are both 0 ?

Homework Equations

The Attempt at a Solution


at the last second line from the bottom , the author gave if P is below the surface of B then water must be out of B and Q1 +Q2 = Q3 ? both statement are contrary to each other
 

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h2 might be a typo for d2?
It might help if you would define Li and di. Qi is volume flow rate, I gather.
 
haruspex said:
h2 might be a typo for d2?
It might help if you would define Li and di. Qi is volume flow rate, I gather.
which h2 is typo for d2 ?
 
foo9008 said:
which h2 is typo for d2 ?
In your post, you quoted a line from the second attachment referencing h2. There is no other h2 in either attachment. I am suggesting the h2 in the attachment might be a typo for d2.
 
haruspex said:
In your post, you quoted a line from the second attachment referencing h2. There is no other h2 in either attachment. I am suggesting the h2 in the attachment might be a typo for d2.
what does h2 mean actually ? why it will = 0 ?
 
foo9008 said:
what does h2 mean actually ? why it will = 0 ?
I don't know, but I might be able to figure it out if you answer the questions I posed in post #2.
 
refrerring to the notes in post 1 , the author said that when P is above the surface of the resevoir B , then water must flow into B and Q1= Q2 + Q3 , why can't the the water from A and B flow to C ?, which is Q1 +Q2 = Q3 ?
 
foo9008 said:
refrerring to the notes in post 1 , the author said that when P is above the surface of the resevoir B , then water must flow into B and Q1= Q2 + Q3 , why can't the the water from A and B flow to C ?, which is Q1 +Q2 = Q3 ?
Imagine closing off the point where the three pipes meet for the moment, so nothing is flowing. The pressure on the A side of that point will exceed the pressure on the B side. So when the joint is opened to allow flow, the A side will win.
This all assumes no drag in the pipes. In the real world, some drag and a narrow pipe on the A side could mean that when water flows there is a large drop in pressure from the A reservoir to the junction, allowing water to enter the junction from B.
 

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