What is the Formula for Calculating Gravity Flow Rate of Water in a Can?

In summary: The gravity flow rate at maximum and minimum levels can be determined by the following equation: v_{max} = \sqrt{2ghc} g : acceleration due to gravity = 9.8m/s2h : height of liquid level in meters, above which the flow rate is maximum (in this case, the level at which the pipe enters the tank)v_{min} = \sqrt{2ghd} g : acceleration due to gravity = 9.8m/s2h : height of liquid level in meters, below which the flow rate is minimum (in this case, the level at which the pipe leaves the tank)
  • #1
dug_rose
3
0
Hi !

I need to find the rate of flow of water coming out of the bottom of a can, under gravity to put in the equation:

r. of f. = speed x area

How do I calculate the speed of which the water drops, taking into account height etc.

Many thanks,

Doug :smile:
 
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  • #2
dug_rose said:
How do I calculate the speed of which the water drops, taking into account height etc.

Many thanks,

Doug :smile:

For that part you would need to use calculus i think. Give me the height of where the water drop starts to fall and i'll reply back.
 
  • #3
hover said:
For that part you would need to use calculus i think. Give me the height of where the water drop starts to fall and i'll reply back.

Hi,

To give you a bit of background we need to drain a can of beer from the bottom of a can into a glass , 25 cm below. What factors effect the speed in which the liquid will drop so I can find the speed and use it to find the flow rate? The can will be on the edge of a table, so 125 cm high say. We are using a 440ml can if that makes any difference, through a machined mild steel pipe. I assuming 9.81 will be a mulitplier somewhere in there?

Thanks for any help you can give me, Doug
 
  • #4
dug_rose said:
Hi,

To give you a bit of background we need to drain a can of beer from the bottom of a can into a glass , 25 cm below. What factors effect the speed in which the liquid will drop so I can find the speed and use it to find the flow rate? The can will be on the edge of a table, so 125 cm high say. We are using a 440ml can if that makes any difference, through a machined mild steel pipe. I assuming 9.81 will be a mulitplier somewhere in there?

Thanks for any help you can give me, Doug


The factors that will affect the speed the drop falls is the acceleration of gravity (9.8m/s) and air resistance.
 
  • #5
Thanks a lot for your help hover
 
  • #6
It will take about half a second for a drop to reach the ground. Using distance/time you will get the average speed of the fall. So 125/.5= 250cm/sec if i am correct. Although i got a answer i don't know if it is totally correct.

hope this helps
 
  • #7
dug: the speed with which the beer starts to flow out the opening in the bottom is proportional to the square root of the level of beer in the can. So, it flows out fastest when the can is full, and the flow rate falls to zero, as the can empties.

A reasonable approximation to the mean outflow speed is given by an application of Bernoulli:

[tex]v_{out} = \sqrt{2gh} [/tex]
g : acceleration due to gravity = 9.8m/s2
h : beer level in can, in meters (some number from 0 to about 0.15m, for a typical can)

It's just one step further to calculate the time it takes to drain the can, for a given hole size.
 
  • #8
Hi, how are you?

Actually i have something to ask also.

I have a adhesive tank 1250kg ( dimension: 1400mm x 1100mm x 900mm) connect to a 11/2"

stainless steel pipe flow to another tank. So, may i know how to calculate the gravity flow

rate at maximum & minimum fluid level and also what is the pipe angle?

Thank you
 

1. What is meant by "rate of flow under gravity"?

The rate of flow under gravity refers to the speed at which a liquid or gas moves through a system under the influence of gravity. This is typically measured in units of volume per unit time, such as liters per second or cubic feet per minute.

2. How is the rate of flow under gravity calculated?

The rate of flow under gravity is calculated using the equation Q = A * v, where Q is the flow rate, A is the cross-sectional area of the system, and v is the velocity of the fluid. This equation is known as the continuity equation and is based on the principle of conservation of mass.

3. What factors affect the rate of flow under gravity?

The rate of flow under gravity can be affected by several factors, including the viscosity of the fluid, the cross-sectional area of the system, and the slope or height of the system. Other factors such as the temperature and pressure of the fluid can also have an impact on the rate of flow.

4. How does the rate of flow under gravity differ from other types of flow?

The rate of flow under gravity differs from other types of flow, such as forced flow or turbulent flow, in that it is driven solely by the force of gravity. In forced flow, an external force, such as a pump, is used to move the fluid, while in turbulent flow, the fluid moves in a chaotic, irregular pattern.

5. Why is the rate of flow under gravity important in scientific research?

The rate of flow under gravity is important in scientific research because it is a fundamental concept in fluid dynamics and is relevant to many natural phenomena, such as the movement of water in rivers and the circulation of air in the atmosphere. Understanding and accurately measuring the rate of flow under gravity is crucial for many fields, including meteorology, hydrology, and engineering.

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