# Multiple Tanks Concept: Changing Water Level Difference

• pranta
Gravitational forces keep water in balance.In summary,The height difference is what is the relevant driver. The ratio of tank areas comes into play as well for the transient behavior.f

#### pranta

Homework Statement
There are two interconnected tanks. Tank 1 having higher water level compare with Tank 2. The connecting pipe lowering the level to align the water level of two tanks and decrease the water level difference. Can you tell me why changing the connection pipe height can change the water level difference?
Relevant Equations
N/A
seeking help for clear concept

I don't understand the problem, but I welcome you, @pranta !

What do you think the answer could be, and why?

I want to know the mechanism why water level difference may influence by changing connection pipe level

I don't understand the problem, but I welcome you, @pranta !

What do you think the answer could be, and why?
yes both could be and why

Homework Statement: There are two interconnected tanks. Tank 1 having higher water level compare with Tank 2. The connecting pipe lowering the level to align the water level of two tanks and decrease the water level difference. Can you tell me why changing the connection pipe height can change the water level difference?
Relevant Equations: N/A

seeking help for clear concept

Can you provide a drawing? Because from how I understand it now the premise is false (the height of the connection pipe will not influence the ultimate height difference between the tanks, which will be zero unless one of the connection points 'runs dry'.

Can you provide a drawing? Because from how I understand it now the premise is false (the height of the connection pipe will not influence the ultimate height difference between the tanks, which will be zero unless one of the connection points 'runs dry'.

#### Attachments

• IMG_0435.jpeg
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here is the picture connection pipe in middle of two tanks. how does it influence the changes of delta H?

here is the picture connection pipe in middle of two tanks. how does it influence the changes of delta H?
Its only has effect in the transient behavior.

so, connection pipe level fluctuations doesn’t affect the water level difference?

so, connection pipe level fluctuations doesn’t affect the water level difference?
Where you put the pipe and its size matter for the transient response i.e. how ##\delta h ## changes in time. There is going to be some decaying fluctuation curve that may have absolute differences ( but similar "shape" responses )

sorry to mention one more information, 1st tank from left side of picture has less volume size than the 2nd tank in right side. does it a factor?

sorry to mention one more information, 1st tank from left side of picture has less volume size than the 2nd tank in right side. does it a factor?
The height difference is what is the relevant driver. The ratio of tank areas comes into play as well for the transient behavior.

Are you trying to determine ##\delta h (t)## given an initial state (a closed valve in the pipe)? Or are you just trying to figure out at what height the system tends to (the steady state response)?

It seems that external water is coming into left tank and water is overflowing right tank?

pranta
It seems that external water is coming into left tank and water is overflowing right tank?
Thats a good point. What are those arrows indicating entering and exiting tank A and B. I may be jumping the gun on believing the OP is accurately describing "the actual system" given that diagram.

Lnewqban
Homework Statement: There are two interconnected tanks. Tank 1 having higher water level compare with Tank 2. The connecting pipe lowering the level to align the water level of two tanks and decrease the water level difference. Can you tell me why changing the connection pipe height can change the water level difference?
Try putting the connecting pipe just below the level of the water shown for the tank on the left.

Lnewqban and erobz
Are you trying to determine ##\delta h (t)## given an initial state (a closed valve in the pipe)? Or are you just trying to figure out at what height the system tends to (the steady state response)?

Try putting the connecting pipe just below the level of the water shown for the tank on the left.
Try putting the connecting pipe just below the level of the water shown for the tank on the left.
do you think that the connection pipe level may affect the water level difference between two tanks?

there is no valve between two tanks

do you think that the connection pipe level may affect the water level difference between two tanks?
Clearly you did not understand what I said. Read it again.

Clearly you did not understand what I said. Read it again.
i didn’t understand. can you explain a bit more

there is no valve between two tanks
Then you aren't telling us the whole story. If there is no valve than this system is being maintained at these levels by an incoming flow on the left tank, and an outgoing flow in the right tank.

Lnewqban and pranta
Then you aren't telling us the whole story. If there is no valve than this system is being maintained at these levels by an incoming flow on the left tank, and an outgoing flow in the right tank.
right just by gravitational flow

right just by gravitational flow
If the tanks are being maintained at the current levels what does that imply for the volumetric flowrate entering tank A and exiting tank B?

If the tanks are being maintained at the current levels what does that imply for the volumetric flowrate entering tank A and exiting tank B?
inflow rate in tank A is higher than the outflow rate in tank B

inflow rate in tank A is higher than the outflow rate in tank B
Is the volume of liquid in either tank changing over time?

Your septic tank needs pumping out : way too much grease.

Tom.G