Water Velocity and Pipe Inclination
Country: United States
Date: June 2006
Hi, am doing a science project on how the velocity
of the flow of water through a pipe is affected by the pipe's
inclination to the horizontal. Can you please tell me how the
angle of inclination affects the velocity of the water and how to
calculate this velocity?
The answer to your question can be extremely complicated
indeed, depending on a number of things you have not made
clear about the experiment. Without knowing the full details,
it is really not possible to begin to answer this question.
As a general statement, water entering from (for example) a
large tank into a pipe that is open at the lower end, will
flow increasingly fast as you tilt the pipe more downward.
This results from what is called the "pressure head" caused
by the weight of the vertical component of the column of
water. Greater pressure (caused by a greater inclination, and
hence a greater vertical drop) causes the water to flow
But how much faster? There is no simple formula for this, and
in fact, most common way to solve this these days involves
using extremely expensive Computational Fluid Dynamics
analysis software. Some things that we need to know, are:
- How is the water entering the pipe? Gravity or pump?
- If it is being pumped, what is the pressure/volume
characteristics of the pump?
- What is the diameter of the pipe?
- What is the surface roughness of the pipe?
- What is the length of the pipe?
- Which direction is the pipe inclined ("up" or "down"?)
Sorry to answer your question with more questions, but this
is actually something that university physics students scratch
their heads on. There is unfortunately no simple formula for
velocity of water in a pipe!
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Update: June 2012