# Homework Help: Flow in branching pipe

1. Mar 10, 2016

### foo9008

1. The problem statement, all variables and given/known data
what does the author mean by if P is below the surface of B then h2 and Q2 are both 0 ?

2. Relevant equations

3. 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

#### Attached Files:

File size:
23.4 KB
Views:
70
• ###### 10.jpg
File size:
51.3 KB
Views:
59
2. Mar 10, 2016

### haruspex

h2 might be a typo for d2?
It might help if you would define Li and di. Qi is volume flow rate, I gather.

3. Mar 11, 2016

### foo9008

which h2 is typo for d2 ?

4. Mar 11, 2016

### haruspex

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.

5. Mar 11, 2016

### foo9008

what does h2 mean actually ? why it will = 0 ?

6. Mar 11, 2016

### haruspex

I don't know, but I might be able to figure it out if you answer the questions I posed in post #2.

7. Mar 20, 2016

### foo9008

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 cant the the water from A and B flow to C ?, which is Q1 +Q2 = Q3 ?

8. Mar 21, 2016

### haruspex

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.