# 3.25: Untitled Page 51

- Page ID
- 18184

## Chapter 3

*Figure 3.11b. * Angle, (

*t*) for draining the system illustrated in *Figure 3.11a*.

*Figure 3.11c. * Angle, (

*t*) for filling the system illustrated in *Figure 3.11a*.

The length and radius of the tank under consideration are given by *L * 8 ft *, *

*R * 1 5

*. * ft

(6)

*Single component systems *

87

Part IIIa. Given the conditions, *Q * 0 4

*. * 5 gal/min and 0 when *t * 0 , use Figure 3.11b to determine the time required to completely drain the tank.

Part IIIb. If the initial depth of the tank is *h * 0 *. * 6 ft and the net flow into the tank is *Q * 0 5

*. * 5 gal/min , use Figure 3.11c to determine the time required to fill the tank. While Figure 3.11c has been constructed on the basis that 2 when *t * 0 , a little thought will indicate that it can be used for other initial conditions.

3‐12. A cylindrical tank of diameter *D* is filled to a depth as illustrated in

o

*h*

Figure 3.12. At *t * 0 a plug is pulled from the bottom of the tank and the *Figure 3.12*. Draining tank

volumetric flow rate through the orifice is given by what is sometimes known as Torricelli’s law (Rouse and Ince, 1957)

*Q * *C A*

o

2

*d*

*p*

(1)

Here *C * is a discharge coefficient having a value of 0.6 and *d*

o

*A * is the area of the

orifice. If the cross‐sectional area of the tank is large compared to the area of the orifice, the pressure in the tank is essentially hydrostatic and *p * is given by

*p * *g h *

(2)

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