a little different tank emptying problem

galactus

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"A square tank is filled with water and has the following dimensions:

sides = 4 ft.
depth = 6 ft

Find the time for it to empty through a one inch diameter circular hole at the tank’s bottom.
Also, assume the flow factor for ordinary small orifices with sharp edges is 0.6
Once you have solved this problem, try calculating the time for your bathtub to empty from a given depth"


I used Torricelli's law to tackle this and arrived at a solution that seems to be too large (an hour and forty minutes). Is anyone versed in how to approach these types of problems when the size of the emptying orifice is included?.
 
Don't know if this will help (Perhaps it's what you already tried?):
visit site:
http://www.eng-tips.com/viewthread.cfm?qid=26687

"Crane's technical paper 410 is a good reference for this.

The formula is Q = 236*di^2*C*(dP/rho)^0.5

Q is the flow rate, gpm
di is the orifice hole, inches
dP is the pressure drop across the orifice in psi which is created by the depth of water in the bucket. I'd take the level of water in the bucket and convert that to psi (2.31 feet of water = 1 psi).
rho is the density of water, 62.4 lb/ft3.
C is the orifice coefficient which depends on the flow rate. Without running some numbers (which Crane has the method for), I'd suggest using 0.6."
 
Thanks, wjm:

The answer I derived is multiplied by 2. That's my error. It should be 49.9 minutes.
 
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