FLUID MECHANICS  CASE STUDY



Introduction

Water Channel 

A city is considering building a water channel which
ends in a free waterfall in a park. A hydraulic engineer is asked to
determine the water surface profile for
a discharge flow rate of 750 ft^{3}/s.
The channel has a trapezoidal shape with a base width of 25 ft, and the
angles on both sides are 30^{o} as
shown in the figure. The slope of the channel is 0.0015. 



Questions


Determine the critical and normal depths,
and identify the surface profile type. Then compute the water
surface profile using the direct step method. 





Approach

Dimensions of the Channel 

 Assume the flow is gradually varied flow.
 Assume the Manning coefficient is 0.025 for gravelly excavated earth
channel*.
* For practices, students are encouraged to repeat this problem
using the Manning coefficient for concrete (shown in the picture). 


