13.3.2. Linear Momentum Equations

Try these first

1. 1.

   What does the mass conservation equation represent in fluid dynamics?

   Hint

   Think about how mass enters and exits a system.

2. 2.

   Define displacement thickness.

   Hint

   Consider how boundary layers affect the streamline.

3. 3.

   What is the primary purpose of the boundary layer concept?

   • To calculate pressure dynamics
   • To analyze velocity and shear stress distribution
   • To measure fluid temperature changes

   Hint

   Think about how engineers assess fluid behavior around structures.

4. 4.

   True or False: The momentum thickness reduces momentum flux in a boundary layer.

   • True
   • False

   Hint

   Recall the definition of momentum thickness.

5. 5.

   Given a flat plate of length 1m in air flowing at a free stream velocity of 25 m/s, calculate the boundary layer thickness if it is laminar. Assume the kinematic viscosity of air as 1.5 x 10^-5 m²/s.

   Hint

   Start by calculating the Reynolds number first.

6. 6.

   In a wind tunnel experiment, a flat plate has a boundary layer formed at its leading edge. Can you derive the shear stress acting on the plate if the velocity gradient at the wall is 2 s^-1 and the dynamic viscosity is 0.001 Pa.s?

   Hint

   Use the shear stress equation from fluid dynamics.