The emptying of a reservoir is a classic theme of fluid mechanics.

The calculation of the fluid velocity is based on the height of water if the reservoir is open.

Torricelli's formula gives us v = v 2g.z

where

g is gravity (9.81ms ²)

z is water depth (m)

The emptying time depends on the relationship between sections of the reservoir and the orifice and varies over time depending on the height of water left in the reservoir.

The formula of the integral gives: Time Drain = S / s. v 2h / g

Where

g is gravity (9.81ms ²)

h water depth (m)

S section of the tank

s section of orifice

The output of the fluid does not form on the surface of the orifice

(section of the jet remains below the section of the hole)

the actual throughput is lower than the theoretical throughput.

We apply a coefficient of flow (discharge coefficient) which verifies: real volumetric flow / theoretical flow =coeff.

With Mecaflux

The emptying time are calculated based on output speeds of the fluid and the water level varies over time depending on speed.

The ejection velocity of the fluid from a pressured reservoir is calculated by selecting "pressure tank" and entering the pressure

To know the output flow (operating point) of a network powered by a tank taking into account losses in the network ,

We must know the operating curve of the reservoir and the curve of operation of our network.
The intersection of 2 curves gives us the operating point.

Curve Network:

1. Calculate the pressure drop at a rate of approximately (unimportant because the flow will be reassessed)
   elements of the section connected to your tank through the inventory of losses.
   Save your inventory loss.

2. Open the graphical analysis (internal flow tools / graphical analysis) and load your registered section.

Curve of the reservoir (allows to know the max speed)

1. select "Search point operation"

2. select "fluid reservoirs"

3. Enter the height of liquid

4. Enter the hole diameter

5. click Create reservoir curve.
   

click on "Start analysis chart"
if it exists, your operating point appears on the graph.
Or is that the flow range is not compatible, we must resize the diameter of orifice...