4.5. Froude Number Relations

Try these first

1. 1.

   What is the formula to calculate the Froude number?

   Hint

   Think about the relationship between velocity, gravity, and depth.

2. 2.

   What is the flow regime when Fr < 1?

   Hint

   Consider what happens to flow characteristics with increased depth.

3. 3.

   What is the definition of the Froude number?

   • A measure of pressure
   • A dimensionless quantity comparing inertia to gravity
   • A calculation of fluid viscosity

   Hint

   Reflect on what the Froude number compares.

4. 4.

   True or False: Supercritical flow occurs when the Froude number is less than 1.

   • True
   • False

   Hint

   Consider the definitions of subcritical and supercritical flow.

5. 5.

   A rectangular channel has a flow velocity of 4 m/s and a depth of 1.5 m. Calculate the Froude number and explain the implications for flow conditions.

   Hint

   Use the flow definition with inertia relating to gravity.

6. 6.

   In a river, the slope is adjusted from 1% to 3%. Discuss how this change affects the Froude number and what flow regime is expected.

   Hint

   Consider how gravity influences motion and the inertia of the water.