The statement that is NOT true about the concept of a boundary layer on an object is: a. the Reynolds number is greater than uni
ty. b. viscous effects are present only inside the boundary layer. c. the fluid velocity is zero at the surface of the object. d. the fluid velocity equals the free stream velocity at the edge of the boundary layer. e. the velocity gradients normal to the flow direction are small.
All the given statements are true except the velocity gradients normal to the flow direction are small since these are not normally small. It's true that viscous effects are present only inside the boundary layer and the fluid velocity equals the free stream velocity at the edge of the boundary layer. Moreover, Reynolds number is greater than unity and the fluid velocity is zero at the surface of the object.
With increased technological knowledge and consequent decreased factors of ignorance, the structures have less inert masses and therefore less need for such decoration. This is the reason why the modern buildings are plainer and depend upon precision of outline and perfection of finish for their architectural effect.
