Open Channel Hydraulics (V.T Chow) Solved Example # 02
Q.No. 02 Verify by computation the depth velocity relationships shown in figure below for the four flow regimes in a wide rectangular open channel. The  
temperature of the water is taken as 68^{°}F. Depth Vs Velocity Chart  
Figure 1  
SOLUTION:  
For verification of type of depth velocity relationship first we will assume a wide  
rectangular channel with a constant width then we will take values of V and Y from  
the given figure and by calculations we will verify our assumptions  
Channel width  =  2  ft  
Flow range & type  =  Subcritical Laminar 1  
Flow Velocity  =  0.2  ft/s  
Flow depth  =  0.02  ft  
Acc gravity  =  32.2  ft/s  
Hydraulic radius  =  0.0196  
υ  =  0.0000108  ft2/s  @ 68F  
Froud No  =  0.25  
Rynold's No  =  364  
For Froud's No 0.25 and Rynold's No 364 it can be verified from Figure.1, that Flow is in Subcritical Laminar 1 
Channel width  =  2  ft  
Flow range & type  =  Supercritical Laminar 2  
Flow Velocity  =  2  ft/s  
Flow depth  =  0.0025  ft  
Acc gravity  =  32.2  ft/s  
Hydraulic radius  =  0.0025  ft  
υ  =  0.0000108  ft2/s  
Froud No  =  7.05  
Rynold's No  =  462  
For Froud' No 7.05 and Rynold's No 462 it can be verified from Figure.1, that Flow is in Supercritical Laminar 2  
Channel width  =  2  ft  
Flow range & type  =  Supercritical Turbulent 3  
Flow Velocity  =  10  ft/s  
Flow depth  =  0.1  ft  
Acc gravity  =  32.2  ft/s  
Hydraulic radius  =  0.0909  ft  
υ  =  0.0000108  ft2/s  
Froud No  =  5.57  
Rynold's No  =  84176  
For Froud's No5.57 and Rynold's No 84176 it can be verified from Figure.1, that Flow is in Supercritical Turbulent 3 

Channel width  =  2  ft  
Flow range & type  =  Subcritical Turbulent 4  
Flow Velocity  =  0.25  ft/s  
Flow depth  =  0.1  ft  
Acc gravity  =  32.2  ft/s  
Hydraulic radius  =  0.0909  ft  
υ  =  0.0000108  ft2/s  
Froud No  =  0.14  
Reynold's No  =  2105  
For Froud's No 0.14 and Rynold's No 2105 it can be verified from Figure.1, that Flow is in Subcritical Turbulent 4 
Also See: Factors Affecting Water Hammer
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