Question

what is the effect of surface roughness and texture on fluid flow and friction?

Answer 1

Surface roughness and texture has a important role over the fluid flow, specially for turbulent flow. If surface area is more, the following phenomena will happen (i) It will increase the surface area, (ii) The pressure drop will be more as there will be more obstacle against fluid flow.

Increase in surface area of pipe will lead to more friction and the friction will restrict the fluid flow. So fluid velocity will decrease.

If pressure drop is more, Newton shear will also be more, that will lead to more obstacle against free flow and will lead to decrease in fluid flow.