- zero velocity at the wall due to high shear stress and high viscosity
- Viscosity is interaction between molecule; when two molecule are far apart the viscosity will be low.
Boundary Layer theory can be classified into two:
It explain abot the flow close to surface and velocity change because of viscosity and fluid resistance. Velocity gradient is largest at the wall and decrease as we go away from the wall. At small distances the velocity gradient is almost = 0.