Question

What fluid property is responsible for the development of the velocity boundary layer? For what kinds of fluids will there be no velocity boundary layer in a pipe?

Short answer

Answer: The fluid property responsible for the development of the velocity boundary layer is viscosity. Fluid types with no boundary layer in a pipe will be the ones with zero viscosity, called inviscid fluids. However, ideal inviscid fluids are only theoretical approximations, and all real fluids exhibit some level of viscosity.

Step-by-step solution

Understanding the concept of the velocity boundary layer

The velocity boundary layer is a region near a solid boundary in which the fluid velocity changes rapidly due to the viscous effects of the fluid. The viscous property of a fluid is responsible for the formation of the boundary layer, which affects the momentum transfer in the fluid flow and creates a drag effect on the solid surfaces.

Identifying the fluid property responsible for the velocity boundary layer

The fluid property responsible for the development of the velocity boundary layer is viscosity. Viscosity is a measure of a fluid's resistance to deformation or the ease with which the layers of fluid flow over one another. It determines the fluid's ability to deform and absorb the momentum of adjacent fluid layers, causing the velocity profile to change near the boundary.

Determining the fluid types with no boundary layer in a pipe

The type of fluids with no velocity boundary layer in a pipe will be the ones with zero viscosity, called inviscid fluids. In inviscid fluids, the layers flow over one another without any resistance, resulting in a smooth flow and no formation of the velocity boundary layer. However, it is important to note that ideal inviscid fluids are only theoretical approximations used for certain calculations, while in reality, all fluids exhibit some level of viscosity.