13.6. Displacement Thickness

Try these first

1. 1.

   Define displacement thickness.

   Hint

   Think about how flow behaves near a surface.

2. 2.

   What does the term boundary layer refer to?

   Hint

   Consider what happens to flow as it moves close to a wall.

3. 3.

   What is the primary effect of displacement thickness?

   • A shift in streamlines
   • An increase in pressure
   • A decrease in fluid density

   Hint

   Consider how the fluid's path changes near solid surfaces.

4. 4.

   True or False: Displacement thickness is always greater than momentum thickness.

   • True
   • False

   Hint

   Think about the definitions of each type of thickness.

5. 5.

   For a laminar flow over a flat plate with the upper velocity of 10 m/s, calculate the displacement thickness at a position where the Reynolds number is 50,000, assuming constant viscosity.

   Hint

   You might need to use the relationships provided in the lecture.

6. 6.

   How does an increase in flow velocity impact the displacement thickness and what implications does this have on drag for an aerodynamic surface?

   Hint

   Consider the relationship between Reynolds number and boundary layer characteristics.