4.3. Velocity Gradient and Shear Stress

Try these first

1. 1.

   What does the no-slip boundary condition imply?

   Hint

   Think about what happens to fluid behavior at a solid boundary.

2. 2.

   Define the velocity gradient in your own words.

   Hint

   Consider the distance away from a surface where fluid velocity changes.

3. 3.

   What is the no-slip boundary condition?

   • The fluid velocity at a boundary is zero.
   • Fluid velocity increases steadily at the boundary.
   • Fluid velocity is constant across all areas.

   Hint

   Consider what happens to fluid at a solid boundary.

4. 4.

   True or False: Shear stress is always constant in the boundary layer.

   • True
   • False

   Hint

   Think about how shear stress relates to fluid dynamics.

5. 5.

   If a fluid with a viscosity of 0.002 Pa.s experiences a velocity gradient of 200 s^-1 at a boundary, calculate the shear stress at that boundary.

   Hint

   Apply the shear stress formula.

6. 6.

   Discuss the impact of a thicker boundary layer on fluid flow and sediment transport in rivers.

   Hint

   Consider how reduced shear stress affects movement.