Question

In any flow over a surface, the effect of viscosity is usually stronger near the surface. True or False?

Answer 1

The statement is true.

In a flow over a surface, the effect of viscosity is usually stronger near the surface because of the boundary layer formation. Boundary-Layer represents the region in which viscous effects are dominant and as we move away from the surface the effect decreases and eventually becomes zero outside the boundary-layer. As we move closer to boundary the vicious effects increases and at the boundary, the fluid sticks to the boundary and this is known as no-slip condition. The fluid layer near to boundary has nearly zero velocity due to high viscous effects.