Fluid Dynamics Problem: Effects of a Full Reservoir

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jmrathbun
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If this isn't the right forum, please move me to a better one.

Assume that the output of a mountain spring is diverted to a reservoir about 200 feet below the spring through the following airtight system:

A two inch pipe leads from the spring to a 40-gallon drum that lies on its side a few feet below the spring; this pipe enters the drum near the top of one end. The drum has three outlets on its other end:
  • At the bottom, a two inch cleanout channel has a short run and is normally closed with a valve
  • In the middle, a 3/4 inch pipe goes down to the top of the reservoir, where there is a short overflow channel of 3/4 inch pipe
  • At the top, a 3/4 inch overflow pipe terminates a few feet below the barrel

The output of the spring is variable. I'm interested in the situation where the reservoir is full and there is more water coming into the barrel than the lower overflow pipe can accommodate. Once the upper overflow pipe fills, does a vacuum form in the barrel that prevents free flow to the reservoir so that the lower overflow pipe would run less full than the upper one?
 
jmrathbun said:
If this isn't the right forum, please move me to a better one.

Assume that the output of a mountain spring is diverted to a reservoir about 200 feet below the spring through the following airtight system:

A two inch pipe leads from the spring to a 40-gallon drum that lies on its side a few feet below the spring; this pipe enters the drum near the top of one end. The drum has three outlets on its other end:
  • At the bottom, a two inch cleanout channel has a short run and is normally closed with a valve
  • In the middle, a 3/4 inch pipe goes down to the top of the reservoir, where there is a short overflow channel of 3/4 inch pipe
  • At the top, a 3/4 inch overflow pipe terminates a few feet below the barrel

The output of the spring is variable. I'm interested in the situation where the reservoir is full and there is more water coming into the barrel than the lower overflow pipe can accommodate. Once the upper overflow pipe fills, does a vacuum form in the barrel that prevents free flow to the reservoir so that the lower overflow pipe would run less full than the upper one?

Can you provide a sketch?

CS
 
Sorry I don't have much in the way of drawing skills but here's my attempt :blushing:
 
Attachments
  • Hand-drawn schematic of a water system: a 2" pipe from a hillside feeds a 40 gallon drum, with a closed cleanout, an upper overflow of 3/4" by 10', and a 3/4" by 200' downhill pipe leading to a cistern with a lower overflow of 3/4" by 10'.
    Spring Feed.jpg
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