2.4. Class Question on Trapezoidal Cross Section

Try these first

1. 1.

   What is the formula for the wetted perimeter in a trapezoidal channel?

   Hint

   Think about the parts of the channel that are in contact with water.

2. 2.

   What does the hydraulic radius indicate?

   Hint

   Recall the formula R_h = A / P.

3. 3.

   What does Manning's equation help calculate in open channel flow?

   • Velocity
   • Pressure
   • Density

   Hint

   Think about what flow characteristics are influenced by channel shape.

4. 4.

   True or False: The Froude number indicates whether a flow is laminar.

   • True
   • False

   Hint

   Remember which numbers indicate flow behavior types.

5. 5.

   Design a trapezoidal canal for a specific flow rate. What dimensions will you choose if the desired flow is 20 m³/s, with a slope of 0.001?

   Hint

   Use Manning's equation for velocity to back out area and then choose dimensions.

6. 6.

   Calculate the effect on the Froude number if the width of a trapezoidal channel is doubled while maintaining depth and flow.

   Hint

   Remember the effect on A and its impact on flow dynamics.