1. Tutorial for CIVL252 Hydraulics Lesson 3 By DUAN Huanfeng ceduan@ust.hk

2. Example 1 Problem –A pipe system consists of a reservoir, a pipe and a valve. The distance from the water surface in the reservoir to the pipe centerline is H. The valve is initially closed. It is desired to establish a steady flow of V 0 in the pipe. How long will it take for the velocity in the pipe to reach 0.99V 0 ? Assume that the pipe is horizontal, the wall shear is given by the Darcy-Weisback equation and the liquid is incompressible. Assume V 0 =10m/s,H=10m,L=2m for an example. H 12 L DV 0

3. Solution For C.V., Momentum EQ. (General form) 12 Control Volume C.V.

7. Now, when the velocity reaches 0.99V 0, Assume, then we can get the relationship curve of a=V t /V 0 to t as following formula and Figure.