The Equation for Volumetric Flow Rate?

In summary, the conversation discusses the use of two equations to calculate Volume Flow Rate (VFR) and how they are both deemed correct. An example problem is given using the equations to determine the volume of water collected in a minute. The conversation also emphasizes the importance of remembering units when solving problems.
  • #1
skoopfadj
8
0
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?
 
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  • #2
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...
 
  • #3
@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)
 
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  • #4
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?
 
  • #5
It should be on there.
7,539.822369 L ?
Thank you very much Mr. Bouwer. (:
 
  • #6
No problem. I see it shows now, didn't the previous one, haha. good job though, correct answer...
 

1. What is the equation for volumetric flow rate?

The equation for volumetric flow rate is Q = A * v, where Q represents the flow rate, A represents the cross-sectional area of the pipe or channel, and v represents the fluid velocity.

2. How is volumetric flow rate different from other types of flow rate?

Volumetric flow rate measures the volume of fluid that passes through a given area per unit time, while other types of flow rate, such as mass flow rate, measure the mass of fluid passing through a given area per unit time.

3. What units are used to measure volumetric flow rate?

Volumetric flow rate can be measured in a variety of units, depending on the system of measurement being used. Common units include cubic meters per second (m3/s), liters per second (L/s), and cubic feet per minute (ft3/min).

4. How is the equation for volumetric flow rate derived?

The equation for volumetric flow rate is derived from the continuity equation, which states that the mass of fluid entering a given area must be equal to the mass of fluid exiting that area. By rearranging the continuity equation and substituting in the definition of flow rate, the equation for volumetric flow rate can be derived.

5. What factors can affect the volumetric flow rate in a system?

The volumetric flow rate in a system can be affected by a variety of factors, including the fluid viscosity, temperature, pressure, and the size and shape of the channel or pipe through which the fluid is flowing. Additionally, any obstructions or restrictions in the flow path can also affect the volumetric flow rate.

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