Flow Rates through a Reservoir
Flow Rates through a Reservoir
(OP)
I have a situation, where i have a reservoirof water 4m (L) x 30cm (W) x 30cm (D). This drains through a 60 mm Pipe places at lowest point. I am wondering how i calculate the flow rate (Litres/min) i will have flowing through this reservoir.
Can anyone advise.
Can anyone advise.





RE: Flow Rates through a Reservoir
Q = C A ( 2 g d2 H )0.5
where:
Q = mass flow rate, kg/s
C = discharge coefficient, typically 0.62
A = cross-sectional area of the drain opening, m2
g = 9.807 m2/s
d = liquid density, kg/m3
H = height of liquid above drain opening, m
If the water height in your reservoir is constantly maintained at the same height (ie., your 30 cm or 0.3 m), then the above equation is valid and Q is the initial, instantaneous flow rate.
But, if your reservoir is allowed to empty, then the final Q = 0 (when H=0). Thus, the average Q while emptying is:
Qaverage = ( Qinitial + 0 ) ÷ 2 = Qinitial ÷ 2
Milton Beychok
(Visit me at www.air-dispersion.com)
.