# CU06997 Lecture 5 ; Exercises

Link to lecture 5

Link naar les 5
Exercise 1

• Water-depth (D) = 1,5 m at P1 and P2
• Discharge Q = 21 m3/s
• Bed width ditch (W) = 4 m
• Slope ditch (S) = 1:3
Questions:

1. Calculate the Hydraulic Radius for the cross-section
2. Calculate Reynolds number
3. Is the flow laminar or turbulent?
4. From which velocity will the flow be laminar, assuming the cross-section stays the same.
5. From which velocity will the flow be turbulent, assuming the cross-section stays the same.
Exercise 2

• Water-depth (D) = 1,5 m at P1
• Water-depth (D) = 1,2 m at P2
• Discharge Q = 21 m3/s
• Bed width ditch (W) = 4 m
• Slope ditch (S) = 1:3
Questions:

1. Calculate the Hydraulic Radius for the cross-section at P2
2. Calculate Reynolds number at P2
3. Is the flow laminar or turbulent?

Exercise 3
Calculate the hydraulic radius for the following cross-sections:

 bed width b [m] water depth y [m] slope [-] 4 1.45 1:3 3 1.37 1:2 5 2.98 1:4 400 3.2 1:0
Exercise 4
Calculate the hydraulic radius for the following partially filled pipes
 Diameter D [m] Water depth h [m] 0.8 0.7 0.7 0.3 3.4 1.7 2.8 2.0

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