What is the mathematical measurement of surface roughness?

[nworm]

Dear Experts!

Do you know any mathematical measurement of roughness of surface?

Thank in advance.

 

[arildno]

In areas where "roughness" matters, rather than the mathematically precise geometry, one usually introduces a "roughness parameter".

For example, in pipe flow (as in your arteries), how wobbly the inside is might significantly affect the actual flow.

However, here, we leave the realm of simply calculable and predictable effects and enters the vast, fascinating world of engineering..