Example 16.2 Transient problem open! Air Initially filled with water pulled out discharge plug near the bottom Water ·average velocity V=√2gh h is the height of water in the tank measured from the center of the hole (a variable) 121.92cmh07 g is the gravitational acceleration,=9.81m/s2 1.27cm Determine: h how long it will take for the water level in the tank to drop to ho/2 from the bottom? 0 Dtank 91.44cm Assumptions: [Textbook Example 5-2] 1.Water is an incompressible substance. 2.The distance between the bottom of the tank and the center of the hole is negligible compared to the total water height. Analysis: take the volume occupied by water as the CV---a variable CV an unsteady-flow problem since the properties within the CV change with time. 上降文通大学 March 26,2019 10 SHANGHAI JIAO TONG UNIVERSITYMarch 26, 2019 10 Example 16.2 Transient problem 121.92cm 91.44 cm open 1.27 cm Determine: how long it will take for the water level in the tank to drop to h0/2 from the bottom? Assumptions: 1. Water is an incompressible substance. 2. The distance between the bottom of the tank and the center of the hole is negligible compared to the total water height. Analysis: • take the volume occupied by water as the CV--- a variable CV • an unsteady-flow problem since the properties within the CV change with time. [Textbook Example 5-2]