Calculating Hole Size for Desired Flow Rate in Tank/Reservoir

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To calculate the hole size needed for a specific flow rate in a tank or reservoir, one can apply energy conservation principles. The kinetic energy of the liquid exiting the hole must equal the work done by the pressure pushing it out. By using the formula Psv = ρsv(v²/2), where P is pressure, s is the area of the hole, and v is the velocity, the relationship between pressure and flow can be established. Ignoring friction simplifies the calculations, allowing for a direct correlation between pressure and the required hole size. This approach effectively determines the necessary dimensions for achieving the desired flow rate.
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Specifically, I have a certain flow rate in (volume/sec) and I know the pressure of the resevoir at a certain point. If there is a hole in the tank/resevoir at that point, how big should it be to achieve the given certain flow rate?
 
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If you may ignore friction, the easiest approach is to use energy conservation. Kinetic energy of liquid flowing out must be equal to work done by pressure pushing this volume out:

P - pressure, s - area of the hole, v - velocity \rho - density of the liquid
Psv = \rho sv\frac{v^2}{2}
thus
P = \frac{\rho v^2}{2}
 


pressure = potential energy
 
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