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-   -   The Equation for Volumetric Flow Rate? (http://www.physicsforums.com/showthread.php?t=655140)

skoopfadj Nov27-12 03:44 AM

The Equation for Volumetric Flow Rate?
 
I'm not sure how to clearly express my query, so I'll round up the gist of it. I understand that this is an entry level question.

I was told that, in order to calculate Volume Flow Rate (VFR), I would use these equations:

* Q = Velocity * Area [EQUATION 1]
* Q = Volume / Time [EQUATION 2]
Units: m^3 / s

Questions:
^Do I use both equations? Are they both deemed correct or only one and which one?
^Can you give an example problem or scenario in which I would use the appropriate equation?

WillemBouwer Nov27-12 04:55 AM

Re: The Equation for Volumetric Flow Rate?
 
Example: You have a pipe with a diameter of 400mm. Water flows through the pipe at a velocity of 1 m/s. Determine how many liters you would have collected in a minute?

Use your equation as you mentioned and come up with a solution, don't et sidetracked by the units, do the first principals correctly...

skoopfadj Nov27-12 05:33 AM

Re: The Equation for Volumetric Flow Rate?
 
@WillemBouwer Correct?

Prompt: A pipe has a diameter of .4 meters. Water flows through the pipe at 1 m/s. Determine how many liters (water) you would have collected in a minute?

Radius: .2 meters (m)
Vinitial: 1 m/s
Volume: ?
Time: 60 seconds

Q = V * A
Q = 1 * (∏(.22))
Q = 0 .1256637061 m3/s

--> Q = V / T
.1256637061 = V / 60
Volume = 7.539822369 m3 or
7.539822369 * 1000 = 7,539.822369 L

1 m3 = 1000 Liters (L)

WillemBouwer Nov27-12 05:41 AM

Re: The Equation for Volumetric Flow Rate?
 
There you go... Using the equation right...
The second equation is just an explaining of the units or terminology, Volume flowrate is exactly that, m^3/s, volume over time. But the first equation is the most commonly used.

However when you get a question, make sure to answer the question as asked with units, always remember your units... But you understand the principal! Cool beans...

So, how many liters per minute?

skoopfadj Nov27-12 05:50 AM

Re: The Equation for Volumetric Flow Rate?
 
It should be on there.
7,539.822369 L ?
Thank you very much Mr. Bouwer. (:

WillemBouwer Nov27-12 06:00 AM

Re: The Equation for Volumetric Flow Rate?
 
No problem. I see it shows now, didn't the previous one, haha. good job though, correct answer...


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